view hgext/evolve.py @ 1183:58370c718183 stable

evolve: use `merge.graft` instead of `rebasenode`

The core mechanism is properly factorised and have a more stable API.
This is also a good step toward removing the dependency between evolve and the
rebase extension.

This also avoid a breakage with the future 3.3 where some of the rebase API
changed.

# Copyright 2011 Peter Arrenbrecht <[e-mail]>
#                Logilab SA        <[e-mail]>
#                Pierre-Yves David <[e-mail]>
#                Patrick Mezard <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''extends Mercurial feature related to Changeset Evolution

This extension provides several commands to mutate history and deal with
issues it may raise.

It also:

    - enables the "Changeset Obsolescence" feature of mercurial,
    - alters core commands and extensions that rewrite history to use
      this feature,
    - improves some aspect of the early implementation in Mercurial core
'''

__version__ = '5.0.1'
testedwith = '3.2'
buglink = 'http://bz.selenic.com/'

import sys, os
import random
from StringIO import StringIO
import struct
import urllib
import re
sha1re = re.compile(r'\b[0-9a-f]{6,40}\b')

import mercurial
from mercurial import util

try:
    from mercurial import obsolete
    if not obsolete._enabled:
        obsolete._enabled = True
    from mercurial import wireproto
    gboptslist = getattr(wireproto, 'gboptslist', None)
    gboptsmap = getattr(wireproto, 'gboptsmap', None)
except (ImportError, AttributeError):
    gboptslist = gboptsmap = None


from mercurial import base85
from mercurial import bookmarks
from mercurial import cmdutil
from mercurial import commands
from mercurial import context
from mercurial import copies
from mercurial import error
from mercurial import exchange
from mercurial import extensions
from mercurial import httppeer
from mercurial import hg
from mercurial import lock as lockmod
from mercurial import merge
from mercurial import node
from mercurial import phases
from mercurial import patch
from mercurial import pushkey
from mercurial import revset
from mercurial import scmutil
from mercurial import templatekw
from mercurial.i18n import _
from mercurial.commands import walkopts, commitopts, commitopts2, mergetoolopts
from mercurial.node import nullid
from mercurial import wireproto
from mercurial import localrepo
from mercurial.hgweb import hgweb_mod
from mercurial import bundle2

cmdtable = {}
command = cmdutil.command(cmdtable)

_pack = struct.pack

if gboptsmap is not None:
    memfilectx = context.memfilectx
elif gboptslist is not None:
    oldmemfilectx = context.memfilectx
    def memfilectx(repo, *args, **kwargs):
        return oldmemfilectx(*args, **kwargs)
else:
    raise util.Abort('Your Mercurial is too old for this version of Evolve\n'
                     'requires version %s or above' % min(testedwith.split()))


# This extension contains the following code
#
# - Extension Helper code
# - Obsolescence cache
# - ...
# - Older format compat


#####################################################################
### Extension helper                                              ###
#####################################################################

class exthelper(object):
    """Helper for modular extension setup

    A single helper should be instanciated for each extension. Helper
    methods are then used as decorator for various purpose.

    All decorators return the original function and may be chained.
    """

    def __init__(self):
        self._uicallables = []
        self._extcallables = []
        self._repocallables = []
        self._revsetsymbols = []
        self._templatekws = []
        self._commandwrappers = []
        self._extcommandwrappers = []
        self._functionwrappers = []
        self._duckpunchers = []

    def final_uisetup(self, ui):
        """Method to be used as the extension uisetup

        The following operations belong here:

        - Changes to ui.__class__ . The ui object that will be used to run the
          command has not yet been created. Changes made here will affect ui
          objects created after this, and in particular the ui that will be
          passed to runcommand
        - Command wraps (extensions.wrapcommand)
        - Changes that need to be visible to other extensions: because
          initialization occurs in phases (all extensions run uisetup, then all
          run extsetup), a change made here will be visible to other extensions
          during extsetup
        - Monkeypatch or wrap function (extensions.wrapfunction) of dispatch
          module members
        - Setup of pre-* and post-* hooks
        - pushkey setup
        """
        for cont, funcname, func in self._duckpunchers:
            setattr(cont, funcname, func)
        for command, wrapper in self._commandwrappers:
            extensions.wrapcommand(commands.table, command, wrapper)
        for cont, funcname, wrapper in self._functionwrappers:
            extensions.wrapfunction(cont, funcname, wrapper)
        for c in self._uicallables:
            c(ui)

    def final_extsetup(self, ui):
        """Method to be used as a the extension extsetup

        The following operations belong here:

        - Changes depending on the status of other extensions. (if
          extensions.find('mq'))
        - Add a global option to all commands
        - Register revset functions
        """
        knownexts = {}
        for name, symbol in self._revsetsymbols:
            revset.symbols[name] = symbol
        for name, kw in self._templatekws:
            templatekw.keywords[name] = kw
        for ext, command, wrapper in self._extcommandwrappers:
            if ext not in knownexts:
                e = extensions.find(ext)
                if e is None:
                    raise util.Abort('extension %s not found' % ext)
                knownexts[ext] = e.cmdtable
            extensions.wrapcommand(knownexts[ext], commands, wrapper)
        for c in self._extcallables:
            c(ui)

    def final_reposetup(self, ui, repo):
        """Method to be used as a the extension reposetup

        The following operations belong here:

        - All hooks but pre-* and post-*
        - Modify configuration variables
        - Changes to repo.__class__, repo.dirstate.__class__
        """
        for c in self._repocallables:
            c(ui, repo)

    def uisetup(self, call):
        """Decorated function will be executed during uisetup

        example::

            @eh.uisetup
            def setupbabar(ui):
                print 'this is uisetup!'
        """
        self._uicallables.append(call)
        return call

    def extsetup(self, call):
        """Decorated function will be executed during extsetup

        example::

            @eh.extsetup
            def setupcelestine(ui):
                print 'this is extsetup!'
        """
        self._extcallables.append(call)
        return call

    def reposetup(self, call):
        """Decorated function will be executed during reposetup

        example::

            @eh.reposetup
            def setupzephir(ui, repo):
                print 'this is reposetup!'
        """
        self._repocallables.append(call)
        return call

    def revset(self, symbolname):
        """Decorated function is a revset symbol

        The name of the symbol must be given as the decorator argument.
        The symbol is added during `extsetup`.

        example::

            @eh.revset('hidden')
            def revsetbabar(repo, subset, x):
                args = revset.getargs(x, 0, 0, 'babar accept no argument')
                return [r for r in subset if 'babar' in repo[r].description()]
        """
        def dec(symbol):
            self._revsetsymbols.append((symbolname, symbol))
            return symbol
        return dec


    def templatekw(self, keywordname):
        """Decorated function is a revset keyword

        The name of the keyword must be given as the decorator argument.
        The symbol is added during `extsetup`.

        example::

            @eh.templatekw('babar')
            def kwbabar(ctx):
                return 'babar'
        """
        def dec(keyword):
            self._templatekws.append((keywordname, keyword))
            return keyword
        return dec

    def wrapcommand(self, command, extension=None):
        """Decorated function is a command wrapper

        The name of the command must be given as the decorator argument.
        The wrapping is installed during `uisetup`.

        If the second option `extension` argument is provided, the wrapping
        will be applied in the extension commandtable. This argument must be a
        string that will be searched using `extension.find` if not found and
        Abort error is raised. If the wrapping applies to an extension, it is
        installed during `extsetup`

        example::

            @eh.wrapcommand('summary')
            def wrapsummary(orig, ui, repo, *args, **kwargs):
                ui.note('Barry!')
                return orig(ui, repo, *args, **kwargs)

        """
        def dec(wrapper):
            if extension is None:
                self._commandwrappers.append((command, wrapper))
            else:
                self._extcommandwrappers.append((extension, command, wrapper))
            return wrapper
        return dec

    def wrapfunction(self, container, funcname):
        """Decorated function is a function wrapper

        This function takes two arguments, the container and the name of the
        function to wrap. The wrapping is performed during `uisetup`.
        (there is no extension support)

        example::

            @eh.function(discovery, 'checkheads')
            def wrapfunction(orig, *args, **kwargs):
                ui.note('His head smashed in and his heart cut out')
                return orig(*args, **kwargs)
        """
        def dec(wrapper):
            self._functionwrappers.append((container, funcname, wrapper))
            return wrapper
        return dec

    def addattr(self, container, funcname):
        """Decorated function is to be added to the container

        This function takes two arguments, the container and the name of the
        function to wrap. The wrapping is performed during `uisetup`.

        example::

            @eh.function(context.changectx, 'babar')
            def babar(ctx):
                return 'babar' in ctx.description
        """
        def dec(func):
            self._duckpunchers.append((container, funcname, func))
            return func
        return dec

eh = exthelper()
uisetup = eh.final_uisetup
extsetup = eh.final_extsetup
reposetup = eh.final_reposetup

#####################################################################
### experimental behavior                                         ###
#####################################################################

commitopts3 = [
    ('D', 'current-date', None,
     _('record the current date as commit date')),
    ('U', 'current-user', None,
     _('record the current user as committer')),
]

def _resolveoptions(ui, opts):
    """modify commit options dict to handle related options

    For now, all it does is figure out the commit date: respect -D unless
    -d was supplied.
    """
    # N.B. this is extremely similar to setupheaderopts() in mq.py
    if not opts.get('date') and opts.get('current_date'):
        opts['date'] = '%d %d' % util.makedate()
    if not opts.get('user') and opts.get('current_user'):
        opts['user'] = ui.username()

getrevs = obsolete.getrevs

#####################################################################
### Additional Utilities                                          ###
#####################################################################

# This section contains a lot of small utility function and method

# - Function to create markers
# - useful alias pstatus and pdiff (should probably go in evolve)
# - "troubles" method on changectx
# - function to travel throught the obsolescence graph
# - function to find useful changeset to stabilize


### Useful alias

@eh.uisetup
def _installalias(ui):
    if ui.config('alias', 'pstatus', None) is None:
        ui.setconfig('alias', 'pstatus', 'status --rev .^')
    if ui.config('alias', 'pdiff', None) is None:
        ui.setconfig('alias', 'pdiff', 'diff --rev .^')
    if ui.config('alias', 'olog', None) is None:
        ui.setconfig('alias', 'olog', "log -r 'precursors(.)' --hidden")
    if ui.config('alias', 'odiff', None) is None:
        ui.setconfig('alias', 'odiff',
            "diff --hidden --rev 'limit(precursors(.),1)' --rev .")
    if ui.config('alias', 'grab', None) is None:
        if os.name == 'nt':
            ui.setconfig('alias', 'grab',
                "! " + util.hgexecutable() + " rebase --dest . --rev $@ && "
                 + util.hgexecutable() + " up tip")
        else:
            ui.setconfig('alias', 'grab',
                "! $HG rebase --dest . --rev $@ && $HG up tip")


### Troubled revset symbol

@eh.revset('troubled')
def revsettroubled(repo, subset, x):
    """``troubled()``
    Changesets with troubles.
    """
    revset.getargs(x, 0, 0, 'troubled takes no arguments')
    return repo.revs('%ld and (unstable() + bumped() + divergent())',
                     subset)


### Obsolescence graph

# XXX SOME MAJOR CLEAN UP TO DO HERE XXX

def _precursors(repo, s):
    """Precursor of a changeset"""
    cs = set()
    nm = repo.changelog.nodemap
    markerbysubj = repo.obsstore.precursors
    for r in s:
        for p in markerbysubj.get(repo[r].node(), ()):
            pr = nm.get(p[0])
            if pr is not None:
                cs.add(pr)
    return cs

def _allprecursors(repo, s):  # XXX we need a better naming
    """transitive precursors of a subset"""
    toproceed = [repo[r].node() for r in s]
    seen = set()
    allsubjects = repo.obsstore.precursors
    while toproceed:
        nc = toproceed.pop()
        for mark in allsubjects.get(nc, ()):
            np = mark[0]
            if np not in seen:
                seen.add(np)
                toproceed.append(np)
    nm = repo.changelog.nodemap
    cs = set()
    for p in seen:
        pr = nm.get(p)
        if pr is not None:
            cs.add(pr)
    return cs

def _successors(repo, s):
    """Successors of a changeset"""
    cs = set()
    nm = repo.changelog.nodemap
    markerbyobj = repo.obsstore.successors
    for r in s:
        for p in markerbyobj.get(repo[r].node(), ()):
            for sub in p[1]:
                sr = nm.get(sub)
                if sr is not None:
                    cs.add(sr)
    return cs

def _allsuccessors(repo, s, haltonflags=0):  # XXX we need a better naming
    """transitive successors of a subset

    haltonflags allows to provide flags which prevent the evaluation of a
    marker.  """
    toproceed = [repo[r].node() for r in s]
    seen = set()
    allobjects = repo.obsstore.successors
    while toproceed:
        nc = toproceed.pop()
        for mark in allobjects.get(nc, ()):
            if mark[2] & haltonflags:
                continue
            for sub in mark[1]:
                if sub == nullid:
                    continue # should not be here!
                if sub not in seen:
                    seen.add(sub)
                    toproceed.append(sub)
    nm = repo.changelog.nodemap
    cs = set()
    for s in seen:
        sr = nm.get(s)
        if sr is not None:
            cs.add(sr)
    return cs




#####################################################################
### Extending revset and template                                 ###
#####################################################################

# this section add several useful revset symbol not yet in core.
# they are subject to changes


### XXX I'm not sure this revset is useful
@eh.revset('suspended')
def revsetsuspended(repo, subset, x):
    """``suspended()``
    Obsolete changesets with non-obsolete descendants.
    """
    args = revset.getargs(x, 0, 0, 'suspended takes no arguments')
    suspended = getrevs(repo, 'suspended')
    return [r for r in subset if r in suspended]


@eh.revset('precursors')
def revsetprecursors(repo, subset, x):
    """``precursors(set)``
    Immediate precursors of changesets in set.
    """
    s = revset.getset(repo, range(len(repo)), x)
    cs = _precursors(repo, s)
    return [r for r in subset if r in cs]


@eh.revset('allprecursors')
def revsetallprecursors(repo, subset, x):
    """``allprecursors(set)``
    Transitive precursors of changesets in set.
    """
    s = revset.getset(repo, range(len(repo)), x)
    cs = _allprecursors(repo, s)
    return [r for r in subset if r in cs]


@eh.revset('successors')
def revsetsuccessors(repo, subset, x):
    """``successors(set)``
    Immediate successors of changesets in set.
    """
    s = revset.getset(repo, range(len(repo)), x)
    cs = _successors(repo, s)
    return [r for r in subset if r in cs]

@eh.revset('allsuccessors')
def revsetallsuccessors(repo, subset, x):
    """``allsuccessors(set)``
    Transitive successors of changesets in set.
    """
    s = revset.getset(repo, range(len(repo)), x)
    cs = _allsuccessors(repo, s)
    return [r for r in subset if r in cs]

### template keywords
# XXX it does not handle troubles well :-/

@eh.templatekw('obsolete')
def obsoletekw(repo, ctx, templ, **args):
    """:obsolete: String. The obsolescence level of the node, could be
    ``stable``, ``unstable``, ``suspended`` or ``extinct``.
    """
    rev = ctx.rev()
    if ctx.obsolete():
        if ctx.extinct():
            return 'extinct'
        else:
            return 'suspended'
    elif ctx.unstable():
        return 'unstable'
    return 'stable'

@eh.templatekw('troubles')
def showtroubles(repo, ctx, **args):
    """:troubles: List of strings. Evolution troubles affecting the changeset
    (zero or more of "unstable", "divergent" or "bumped")."""
    return templatekw.showlist('trouble', ctx.troubles(), plural='troubles',
                               **args)

#####################################################################
### Various trouble warning                                       ###
#####################################################################

# This section take care of issue warning to the user when troubles appear

@eh.wrapcommand("update")
@eh.wrapcommand("parents")
@eh.wrapcommand("pull")
def wrapmayobsoletewc(origfn, ui, repo, *args, **opts):
    """Warn that the working directory parent is an obsolete changeset"""
    res = origfn(ui, repo, *args, **opts)
    if repo['.'].obsolete():
        ui.warn(_('working directory parent is obsolete!\n'))
    return res

# XXX this could wrap transaction code
# XXX (but this is a bit a layer violation)
@eh.wrapcommand("commit")
@eh.wrapcommand("import")
@eh.wrapcommand("push")
@eh.wrapcommand("pull")
@eh.wrapcommand("graft")
@eh.wrapcommand("phase")
@eh.wrapcommand("unbundle")
def warnobserrors(orig, ui, repo, *args, **kwargs):
    """display warning is the command resulted in more instable changeset"""
    # part of the troubled stuff may be filtered (stash ?)
    # This needs a better implementation but will probably wait for core.
    filtered = repo.changelog.filteredrevs
    priorunstables = len(set(getrevs(repo, 'unstable')) - filtered)
    priorbumpeds = len(set(getrevs(repo, 'bumped')) - filtered)
    priordivergents = len(set(getrevs(repo, 'divergent')) - filtered)
    ret = orig(ui, repo, *args, **kwargs)
    # workaround phase stupidity
    #phases._filterunknown(ui, repo.changelog, repo._phasecache.phaseroots)
    filtered = repo.changelog.filteredrevs
    newunstables = \
        len(set(getrevs(repo, 'unstable')) - filtered) - priorunstables
    newbumpeds = \
        len(set(getrevs(repo, 'bumped')) - filtered) - priorbumpeds
    newdivergents = \
        len(set(getrevs(repo, 'divergent')) - filtered) - priordivergents
    if newunstables > 0:
        ui.warn(_('%i new unstable changesets\n') % newunstables)
    if newbumpeds > 0:
        ui.warn(_('%i new bumped changesets\n') % newbumpeds)
    if newdivergents > 0:
        ui.warn(_('%i new divergent changesets\n') % newdivergents)
    return ret

@eh.wrapfunction(mercurial.exchange, 'push')
def push(orig, repo, *args, **opts):
    """Add a hint for "hg evolve" when troubles make push fails
    """
    try:
        return orig(repo, *args, **opts)
    except util.Abort, ex:
        hint = _("use 'hg evolve' to get a stable history "
                 "or --force to ignore warnings")
        if (len(ex.args) >= 1
            and ex.args[0].startswith('push includes ')
            and ex.hint is None):
            ex.hint = hint
        raise
    return result

def summaryhook(ui, repo):
    def write(fmt, count):
        s = fmt % count
        if count:
            ui.write(s)
        else:
            ui.note(s)

    nbunstable = len(getrevs(repo, 'unstable'))
    nbbumped = len(getrevs(repo, 'bumped'))
    nbdivergent = len(getrevs(repo, 'divergent'))
    write('unstable: %i changesets\n', nbunstable)
    write('bumped: %i changesets\n', nbbumped)
    write('divergent: %i changesets\n', nbdivergent)

@eh.extsetup
def obssummarysetup(ui):
    cmdutil.summaryhooks.add('evolve', summaryhook)


#####################################################################
### Core Other extension compat                                   ###
#####################################################################


@eh.extsetup
def _rebasewrapping(ui):
    # warning about more obsolete
    try:
        rebase = extensions.find('rebase')
        if rebase:
            extensions.wrapcommand(rebase.cmdtable, 'rebase', warnobserrors)
    except KeyError:
        pass  # rebase not found
    try:
        histedit = extensions.find('histedit')
        if histedit:
            extensions.wrapcommand(histedit.cmdtable, 'histedit', warnobserrors)
    except KeyError:
        pass  # rebase not found

#####################################################################
### Old Evolve extension content                                  ###
#####################################################################

# XXX need clean up and proper sorting in other section

### util function
#############################

### changeset rewriting logic
#############################

def rewrite(repo, old, updates, head, newbases, commitopts):
    """Return (nodeid, created) where nodeid is the identifier of the
    changeset generated by the rewrite process, and created is True if
    nodeid was actually created. If created is False, nodeid
    references a changeset existing before the rewrite call.
    """
    if len(old.parents()) > 1: #XXX remove this unecessary limitation.
        raise error.Abort(_('cannot amend merge changesets'))
    base = old.p1()
    updatebookmarks = _bookmarksupdater(repo, old.node())

    # commit a new version of the old changeset, including the update
    # collect all files which might be affected
    files = set(old.files())
    for u in updates:
        files.update(u.files())

    # Recompute copies (avoid recording a -> b -> a)
    copied = copies.pathcopies(base, head)


    # prune files which were reverted by the updates
    def samefile(f):
        if f in head.manifest():
            a = head.filectx(f)
            if f in base.manifest():
                b = base.filectx(f)
                return (a.data() == b.data()
                        and a.flags() == b.flags())
            else:
                return False
        else:
            return f not in base.manifest()
    files = [f for f in files if not samefile(f)]
    # commit version of these files as defined by head
    headmf = head.manifest()
    def filectxfn(repo, ctx, path):
        if path in headmf:
            fctx = head[path]
            flags = fctx.flags()
            mctx = memfilectx(repo, fctx.path(), fctx.data(),
                              islink='l' in flags,
                              isexec='x' in flags,
                              copied=copied.get(path))
            return mctx
        return None

    message = cmdutil.logmessage(repo.ui, commitopts)
    if not message:
        message = old.description()

    user = commitopts.get('user') or old.user()
    date = commitopts.get('date') or None # old.date()
    extra = dict(commitopts.get('extra', {}))
    extra['branch'] = head.branch()

    new = context.memctx(repo,
                         parents=newbases,
                         text=message,
                         files=files,
                         filectxfn=filectxfn,
                         user=user,
                         date=date,
                         extra=extra)

    if commitopts.get('edit'):
        new._text = cmdutil.commitforceeditor(repo, new, [])
    revcount = len(repo)
    newid = repo.commitctx(new)
    new = repo[newid]
    created = len(repo) != revcount
    updatebookmarks(newid)

    return newid, created

class MergeFailure(util.Abort):
    pass

def relocate(repo, orig, dest, keepbranch=False):
    """rewrite <rev> on dest"""
    if orig.rev() == dest.rev():
        raise util.Abort(_('tried to relocate a node on top of itself'),
                         hint=_("This shouldn't happen. If you still "
                                "need to move changesets, please do so "
                                "manually with nothing to rebase - working "
                                "directory parent is also destination"))

    rebase = extensions.find('rebase')
    # dummy state to trick rebase node
    if not orig.p2().rev() == node.nullrev:
        raise util.Abort(
            'no support for evolving merge changesets yet',
            hint="Redo the merge and use `hg prune <old> --succ <new>` to obsolete the old one")
    destbookmarks = repo.nodebookmarks(dest.node())
    nodesrc = orig.node()
    destphase = repo[nodesrc].phase()
    commitmsg = orig.description()

    cache = {}
    sha1s = re.findall(sha1re, commitmsg)
    unfi = repo.unfiltered()
    for sha1 in sha1s:
        ctx = None
        try:
            ctx = unfi[sha1]
        except error.RepoLookupError:
            continue

        if not ctx.obsolete():
            continue

        successors = obsolete.successorssets(repo, ctx.node(), cache)

        # We can't make any assumptions about how to update the hash if the
        # cset in question was split or diverged.
        if len(successors) == 1 and len(successors[0]) == 1:
            newsha1 = node.hex(successors[0][0])
            commitmsg = commitmsg.replace(sha1, newsha1[:len(sha1)])
        else:
            repo.ui.note(_('The stale commit message reference to %s could '
                           'not be updated\n') % sha1)

    tr = repo.transaction('relocate')
    try:
        try:
            if repo['.'].rev() != dest.rev():
                merge.update(repo, dest, False, True, False)
            r = merge.graft(repo, orig, orig.p1(),
                                   ['local', 'graft'])
            if r[-1]: #some conflict
                raise util.Abort(
                        'unresolved merge conflicts (see hg help resolve)')
            if keepbranch:
                def _extrafn(ctx, extra):
                    extra['branch'] = ctx.branch()
            else:
                _extrafn = (lambda ctx, extra: None)

            nodenew = rebase.concludenode(repo, orig.node(), dest.node(),
                                          node.nullid, commitmsg,
                                          extrafn=_extrafn)
        except util.Abort, exc:
            repo.dirstate.beginparentchange()
            repo.setparents(repo['.'].node(), nullid)
            repo.dirstate.write()
            # fix up dirstate for copies and renames
            copies.duplicatecopies(repo, dest.rev(), orig.p1().rev())
            repo.dirstate.endparentchange()
            class LocalMergeFailure(MergeFailure, exc.__class__):
                pass
            exc.__class__ = LocalMergeFailure
            raise
        oldbookmarks = repo.nodebookmarks(nodesrc)
        if nodenew is not None:
            phases.retractboundary(repo, tr, destphase, [nodenew])
            obsolete.createmarkers(repo, [(repo[nodesrc], (repo[nodenew],))])
            for book in oldbookmarks:
                repo._bookmarks[book] = nodenew
        else:
            obsolete.createmarkers(repo, [(repo[nodesrc], ())])
            # Behave like rebase, move bookmarks to dest
            for book in oldbookmarks:
                repo._bookmarks[book] = dest.node()
        for book in destbookmarks: # restore bookmark that rebase move
            repo._bookmarks[book] = dest.node()
        if oldbookmarks or destbookmarks:
            repo._bookmarks.write()
        tr.close()
    finally:
        tr.release()
    return nodenew

def _bookmarksupdater(repo, oldid):
    """Return a callable update(newid) updating the current bookmark
    and bookmarks bound to oldid to newid.
    """
    bm = bookmarks.readcurrent(repo)
    def updatebookmarks(newid):
        dirty = False
        if bm:
            repo._bookmarks[bm] = newid
            dirty = True
        oldbookmarks = repo.nodebookmarks(oldid)
        if oldbookmarks:
            for b in oldbookmarks:
                repo._bookmarks[b] = newid
            dirty = True
        if dirty:
            repo._bookmarks.write()
    return updatebookmarks

### new command
#############################
metadataopts = [
    ('d', 'date', '',
     _('record the specified date in metadata'), _('DATE')),
    ('u', 'user', '',
     _('record the specified user in metadata'), _('USER')),
]

@eh.uisetup
def _installimportobsolete(ui):
    entry = cmdutil.findcmd('import', commands.table)[1]
    entry[1].append(('', 'obsolete', False,
                    _('mark the old node as obsoleted by '
                      'the created commit')))

@eh.wrapfunction(mercurial.cmdutil, 'tryimportone')
def tryimportone(orig, ui, repo, hunk, parents, opts, *args, **kwargs):
    extracted = patch.extract(ui, hunk)
    expected = extracted[5]
    if expected is not None:
        expected = node.bin(expected)
    oldextract = patch.extract
    try:
        patch.extract = lambda ui, hunk: extracted
        ret = orig(ui, repo, hunk, parents, opts, *args, **kwargs)
    finally:
        patch.extract = oldextract
    created = ret[1]
    if (opts['obsolete'] and None not in (created, expected)
        and created != expected):
            tr = repo.transaction('import-obs')
            try:
                metadata = {'user': ui.username()}
                repo.obsstore.create(tr, expected, (created,),
                                     metadata=metadata)
                tr.close()
            finally:
                tr.release()
    return ret


def _deprecatealias(oldalias, newalias):
    '''Deprecates an alias for a command in favour of another

    Creates a new entry in the command table for the old alias. It creates a
    wrapper that has its synopsis set to show that is has been deprecated.
    The documentation will be replace with a pointer to the new alias.
    If a user invokes the command a deprecation warning will be printed and
    the command of the *new* alias will be invoked.

    This function is loosely based on the extensions.wrapcommand function.
    '''
    aliases, entry = cmdutil.findcmd(newalias, cmdtable)
    for alias, e in cmdtable.iteritems():
        if e is entry:
            break

    synopsis = '(DEPRECATED)'
    if len(entry) > 2:
        fn, opts, _syn = entry
    else:
        fn, opts, = entry
    deprecationwarning = _('%s have been deprecated in favor of %s\n' % (
        oldalias, newalias))
    def newfn(*args, **kwargs):
        ui = args[0]
        ui.warn(deprecationwarning)
        util.checksignature(fn)(*args, **kwargs)
    newfn.__doc__  = deprecationwarning
    cmdwrapper = command(oldalias, opts, synopsis)
    cmdwrapper(newfn)

@eh.extsetup
def deprecatealiases(ui):
    _deprecatealias('gup', 'next')
    _deprecatealias('gdown', 'previous')

@command('debugrecordpruneparents', [], '')
def cmddebugrecordpruneparents(ui, repo):
    """add parents data to prune markers when possible

    This commands search the repo for prune markers without parent information.
    If the pruned node is locally known, a new markers with parent data is
    created."""
    pgop = 'reading markers'

    # lock from the beginning to prevent race
    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('recordpruneparents')
        unfi = repo.unfiltered()
        nm = unfi.changelog.nodemap
        store = repo.obsstore
        pgtotal = len(store._all)
        for idx, mark in enumerate(list(store._all)):
            if not mark[1]:
                rev = nm.get(mark[0])
                if rev is not None:
                    ctx = unfi[rev]
                    meta = obsolete.decodemeta(mark[3])
                    for i, p in enumerate(ctx.parents(), 1):
                        meta['p%i' % i] = p.hex()
                    before = len(store._all)
                    store.create(tr, mark[0], mark[1], mark[2], metadata=meta)
                    if len(store._all) - before:
                        ui.write('created new markers for %i\n' % rev)
            ui.progress(pgop, idx, total=pgtotal)
        tr.close()
        ui.progress(pgop, None)
    finally:
        lockmod.release(tr, lock, wlock)

@command('debugobsstorestat', [], '')
def cmddebugobsstorestat(ui, repo):
    """print statistic about obsolescence markers in the repo"""
    store = repo.obsstore
    unfi = repo.unfiltered()
    nm = unfi.changelog.nodemap
    ui.write('markers total:              %9i\n' % len(store._all))
    sucscount = [0, 0 , 0, 0]
    known = 0
    parentsdata = 0
    metakeys = {}
    # node -> cluster mapping
    #   a cluster is a (set(nodes), set(markers)) tuple
    clustersmap = {}
    # same data using parent information
    pclustersmap= {}
    for mark in store:
        if mark[0] in nm:
            known += 1
        nbsucs = len(mark[1])
        sucscount[min(nbsucs, 3)] += 1
        meta = mark[3]
        for key, value in meta:
            metakeys.setdefault(key, 0)
            metakeys[key] += 1
        meta = dict(meta)
        parents = [meta.get('p1'), meta.get('p2')]
        parents = [node.bin(p) for p in parents if p is not None]
        if parents:
            parentsdata += 1
        # cluster handling
        nodes = set()
        nodes.add(mark[0])
        nodes.update(mark[1])
        c = (set(nodes), set([mark]))

        toproceed = set(nodes)
        while toproceed:
            n = toproceed.pop()
            other = clustersmap.get(n)
            if (other is not None
                and other is not c):
                other[0].update(c[0])
                other[1].update(c[1])
                for on in c[0]:
                    if on in toproceed:
                        continue
                    clustersmap[on] = other
                c = other
            clustersmap[n] = c
        # same with parent data
        nodes.update(parents)
        c = (set(nodes), set([mark]))
        toproceed = set(nodes)
        while toproceed:
            n = toproceed.pop()
            other = pclustersmap.get(n)
            if (other is not None
                and other is not c):
                other[0].update(c[0])
                other[1].update(c[1])
                for on in c[0]:
                    if on in toproceed:
                        continue
                    pclustersmap[on] = other
                c = other
            pclustersmap[n] = c

    # freezing the result
    for c in clustersmap.values():
        fc = (frozenset(c[0]), frozenset(c[1]))
        for n in fc[0]:
            clustersmap[n] = fc
    # same with parent data
    for c in pclustersmap.values():
        fc = (frozenset(c[0]), frozenset(c[1]))
        for n in fc[0]:
            pclustersmap[n] = fc
    ui.write('    for known precursors:   %9i\n' % known)
    ui.write('    with parents data:      %9i\n' % parentsdata)
    # successors data
    ui.write('markers with no successors: %9i\n' % sucscount[0])
    ui.write('              1 successors: %9i\n' % sucscount[1])
    ui.write('              2 successors: %9i\n' % sucscount[2])
    ui.write('    more than 2 successors: %9i\n' % sucscount[3])
    # meta data info
    ui.write('    available  keys:\n')
    for key in sorted(metakeys):
        ui.write('    %15s:        %9i\n' % (key, metakeys[key]))

    allclusters = list(set(clustersmap.values()))
    allclusters.sort(key=lambda x: len(x[1]))
    ui.write('disconnected clusters:      %9i\n' % len(allclusters))

    ui.write('        any known node:     %9i\n'
             % len([c for c in allclusters
                    if [n for n in c[0] if nm.get(n) is not None]]))
    if allclusters:
        nbcluster = len(allclusters)
        ui.write('        smallest length:    %9i\n' % len(allclusters[0][1]))
        ui.write('        longer length:      %9i\n' % len(allclusters[-1][1]))
        median = len(allclusters[nbcluster//2][1])
        ui.write('        median length:      %9i\n' % median)
        mean = sum(len(x[1]) for x in allclusters) // nbcluster
        ui.write('        mean length:        %9i\n' % mean)
    allpclusters = list(set(pclustersmap.values()))
    allpclusters.sort(key=lambda x: len(x[1]))
    ui.write('    using parents data:     %9i\n' % len(allpclusters))
    ui.write('        any known node:     %9i\n'
             % len([c for c in allclusters
                    if [n for n in c[0] if nm.get(n) is not None]]))
    if allpclusters:
        nbcluster = len(allpclusters)
        ui.write('        smallest length:    %9i\n' % len(allpclusters[0][1]))
        ui.write('        longer length:      %9i\n' % len(allpclusters[-1][1]))
        median = len(allpclusters[nbcluster//2][1])
        ui.write('        median length:      %9i\n' % median)
        mean = sum(len(x[1]) for x in allpclusters) // nbcluster
        ui.write('        mean length:        %9i\n' % mean)

@command('^evolve|stabilize|solve',
    [('n', 'dry-run', False,
        'do not perform actions, just print what would be done'),
     ('', 'confirm', False,
        'ask for confirmation before performing the action'),
    ('A', 'any', False, 'also consider troubled changesets unrelated to current working directory'),
    ('a', 'all', False, 'evolve all troubled changesets in the repo '
                        '(implies any)'),
    ('c', 'continue', False, 'continue an interrupted evolution'),
    ] + mergetoolopts,
    _('[OPTIONS]...'))
def evolve(ui, repo, **opts):
    """solve trouble in your repository

    - rebase unstable changesets to make them stable again,
    - create proper diffs from bumped changesets,
    - merge divergent changesets,
    - update to a successor if the working directory parent is
      obsolete

    By default a single changeset is evolved for each invocation and only
    troubled changesets that would evolve as a descendant of the current
    working directory will be considered. See --all and --any options to change
    this behavior.

    - For unstable, this means taking the first which could be rebased as a
      child of the working directory parent revision or one of its descendants
      and rebasing it.

    - For divergent, this means taking "." if applicable.

    With --any, evolve picks any troubled changeset to repair.

    The working directory is updated to the newly created revision.
    """

    contopt = opts['continue']
    anyopt = opts['any']
    allopt = opts['all']
    dryrunopt = opts['dry_run']
    confirmopt = opts['confirm']
    ui.setconfig('ui', 'forcemerge', opts.get('tool', ''), 'evolve')

    startnode = repo['.']

    if contopt:
        if anyopt:
            raise util.Abort('cannot specify both "--any" and "--continue"')
        if allopt:
            raise util.Abort('cannot specify both "--all" and "--continue"')
        graftcmd = commands.table['graft'][0]
        return graftcmd(ui, repo, old_obsolete=True, **{'continue': True})

    tro = _picknexttroubled(ui, repo, anyopt or allopt)
    if tro is None:
        if repo['.'].obsolete():
            displayer = cmdutil.show_changeset(
                ui, repo, {'template': shorttemplate})
            successors = set()

            for successorsset in obsolete.successorssets(repo, repo['.'].node()):
                for nodeid in successorsset:
                    successors.add(repo[nodeid])

            if not successors:
                ui.warn(_('parent is obsolete without successors; ' +
                          'likely killed\n'))
                return 2

            elif len(successors) > 1:
                ui.warn(_('parent is obsolete with multiple successors:\n'))

                for ctx in sorted(successors, key=lambda ctx: ctx.rev()):
                    displayer.show(ctx)

                return 2

            else:
                ctx = successors.pop()

                ui.status(_('update:'))
                if not ui.quiet:
                    displayer.show(ctx)

                if dryrunopt:
                    return 0
                else:
                    res = hg.update(repo, ctx.rev())
                    if ctx != startnode:
                        ui.status(_('working directory is now at %s\n') % ctx)
                    return res

        troubled = repo.revs('troubled()')
        if troubled:
            ui.write_err(_('nothing to evolve here\n'))
            ui.status(_('(%i troubled changesets, do you want --any ?)\n')
                      % len(troubled))
            return 2
        else:
            ui.write_err(_('no troubled changesets\n'))
            return 1

    def progresscb():
        if allopt:
            ui.progress('evolve', seen, unit='changesets', total=count)
    seen = 1
    count = allopt and _counttroubled(ui, repo) or 1

    while tro is not None:
        progresscb()
        wlock = lock = tr = None
        try:
            wlock = repo.wlock()
            lock = repo.lock()
            tr = repo.transaction("evolve")
            result = _evolveany(ui, repo, tro, dryrunopt, confirmopt,
                                progresscb=progresscb)
            tr.close()
        finally:
            lockmod.release(tr, lock, wlock)
        progresscb()
        seen += 1
        if not allopt:
            if repo['.'] != startnode:
                ui.status(_('working directory is now at %s\n') % repo['.'])
            return result
        progresscb()
        tro = _picknexttroubled(ui, repo, anyopt or allopt)

    if allopt:
        ui.progress('evolve', None)

    if repo['.'] != startnode:
        ui.status(_('working directory is now at %s\n') % repo['.'])


def _evolveany(ui, repo, tro, dryrunopt, confirmopt, progresscb):
    repo = repo.unfiltered()
    tro = repo[tro.rev()]
    cmdutil.bailifchanged(repo)
    troubles = tro.troubles()
    if 'unstable' in troubles:
        return _solveunstable(ui, repo, tro, dryrunopt, confirmopt, progresscb)
    elif 'bumped' in troubles:
        return _solvebumped(ui, repo, tro, dryrunopt, confirmopt, progresscb)
    elif 'divergent' in troubles:
        repo = repo.unfiltered()
        tro = repo[tro.rev()]
        return _solvedivergent(ui, repo, tro, dryrunopt, confirmopt,
                               progresscb)
    else:
        assert False  # WHAT? unknown troubles

def _counttroubled(ui, repo):
    """Count the amount of troubled changesets"""
    troubled = set()
    troubled.update(getrevs(repo, 'unstable'))
    troubled.update(getrevs(repo, 'bumped'))
    troubled.update(getrevs(repo, 'divergent'))
    return len(troubled)

def _picknexttroubled(ui, repo, pickany=False, progresscb=None):
    """Pick a the next trouble changeset to solve"""
    if progresscb: progresscb()
    tro = _stabilizableunstable(repo, repo['.'])
    if tro is None:
        wdp = repo['.']
        if 'divergent' in wdp.troubles():
            tro = wdp
    if tro is None and pickany:
        troubled = list(repo.set('unstable()'))
        if not troubled:
            troubled = list(repo.set('bumped()'))
        if not troubled:
            troubled = list(repo.set('divergent()'))
        if troubled:
            tro = troubled[0]

    return tro

def _stabilizableunstable(repo, pctx):
    """Return a changectx for an unstable changeset which can be
    stabilized on top of pctx or one of its descendants. None if none
    can be found.
    """
    def selfanddescendants(repo, pctx):
        yield pctx
        for prec in repo.set('allprecursors(%d)', pctx):
            yield prec
        for ctx in pctx.descendants():
            yield ctx
            for prec in repo.set('allprecursors(%d)', ctx):
                yield prec

    # Look for an unstable which can be stabilized as a child of
    # node. The unstable must be a child of one of node predecessors.
    directdesc = set([pctx.rev()])
    for ctx in selfanddescendants(repo, pctx):
        for child in ctx.children():
            if ctx.rev() in directdesc and not child.obsolete():
                directdesc.add(child.rev())
            elif child.unstable():
                return child
    return None

def _solveunstable(ui, repo, orig, dryrun=False, confirm=False,
                   progresscb=None):
    """Stabilize a unstable changeset"""
    obs = orig.parents()[0]
    if not obs.obsolete():
        obs = orig.parents()[1] # second parent is obsolete ?
    assert obs.obsolete()
    newer = obsolete.successorssets(repo, obs.node())
    # search of a parent which is not killed
    while not newer or newer == [()]:
        ui.debug("stabilize target %s is plain dead,"
                 " trying to stabilize on its parent\n" %
                 obs)
        obs = obs.parents()[0]
        newer = obsolete.successorssets(repo, obs.node())
    if len(newer) > 1:
        raise util.Abort(_("conflict rewriting. can't choose destination\n"))
    targets = newer[0]
    assert targets
    if len(targets) > 1:
        raise util.Abort(_("does not handle split parents yet\n"))
        return 2
    target = targets[0]
    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    target = repo[target]
    if not ui.quiet or confirm:
        repo.ui.write(_('move:'))
        displayer.show(orig)
        repo.ui.write(_('atop:'))
        displayer.show(target)
    if confirm and ui.prompt('perform evolve? [Ny]') != 'y':
            raise util.Abort(_('evolve aborted by user'))
    if progresscb: progresscb()
    todo = 'hg rebase -r %s -d %s\n' % (orig, target)
    if dryrun:
        repo.ui.write(todo)
    else:
        repo.ui.note(todo)
        if progresscb: progresscb()
        keepbranch = orig.p1().branch() != orig.branch()
        try:
            relocate(repo, orig, target, keepbranch)
        except MergeFailure:
            repo.opener.write('graftstate', orig.hex() + '\n')
            repo.ui.write_err(_('evolve failed!\n'))
            repo.ui.write_err(
                _('fix conflict and run "hg evolve --continue"\n'))
            raise

def _solvebumped(ui, repo, bumped, dryrun=False, confirm=False,
                 progresscb=None):
    """Stabilize a bumped changeset"""
    # For now we deny bumped merge
    if len(bumped.parents()) > 1:
        raise util.Abort('late comer stabilization is confused by bumped'
                         ' %s being a merge' % bumped)
    prec = repo.set('last(allprecursors(%d) and public())', bumped).next()
    # For now we deny target merge
    if len(prec.parents()) > 1:
        raise util.Abort('late comer evolution is confused by precursors'
                         ' %s being a merge' % prec)

    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if not ui.quiet or confirm:
        repo.ui.write(_('recreate:'))
        displayer.show(bumped)
        repo.ui.write(_('atop:'))
        displayer.show(prec)
    if confirm and ui.prompt('perform evolve? [Ny]') != 'y':
        raise util.Abort(_('evolve aborted by user'))
    if dryrun:
        todo = 'hg rebase --rev %s --dest %s;\n' % (bumped, prec.p1())
        repo.ui.write(todo)
        repo.ui.write('hg update %s;\n' % prec)
        repo.ui.write('hg revert --all --rev %s;\n' % bumped)
        repo.ui.write('hg commit --msg "bumped update to %s"')
        return 0
    if progresscb: progresscb()
    newid = tmpctx = None
    tmpctx = bumped
    bmupdate = _bookmarksupdater(repo, bumped.node())
    # Basic check for common parent. Far too complicated and fragile
    tr = repo.transaction('bumped-stabilize')
    try:
        if not list(repo.set('parents(%d) and parents(%d)', bumped, prec)):
            # Need to rebase the changeset at the right place
            repo.ui.status(
                _('rebasing to destination parent: %s\n') % prec.p1())
            try:
                tmpid = relocate(repo, bumped, prec.p1())
                if tmpid is not None:
                    tmpctx = repo[tmpid]
                    obsolete.createmarkers(repo, [(bumped, (tmpctx,))])
            except MergeFailure:
                repo.opener.write('graftstate', bumped.hex() + '\n')
                repo.ui.write_err(_('evolution failed!\n'))
                repo.ui.write_err(
                    _('fix conflict and run "hg evolve --continue"\n'))
                raise
        # Create the new commit context
        repo.ui.status(_('computing new diff\n'))
        files = set()
        copied = copies.pathcopies(prec, bumped)
        precmanifest = prec.manifest()
        for key, val in bumped.manifest().items():
            if precmanifest.pop(key, None) != val:
                files.add(key)
        files.update(precmanifest)  # add missing files
        # commit it
        if files: # something to commit!
            def filectxfn(repo, ctx, path):
                if path in bumped:
                    fctx = bumped[path]
                    flags = fctx.flags()
                    mctx = memfilectx(repo, fctx.path(), fctx.data(),
                                      islink='l' in flags,
                                      isexec='x' in flags,
                                      copied=copied.get(path))
                    return mctx
                return None
            text = 'bumped update to %s:\n\n' % prec
            text += bumped.description()

            new = context.memctx(repo,
                                 parents=[prec.node(), node.nullid],
                                 text=text,
                                 files=files,
                                 filectxfn=filectxfn,
                                 user=bumped.user(),
                                 date=bumped.date(),
                                 extra=bumped.extra())

            newid = repo.commitctx(new)
        if newid is None:
            obsolete.createmarkers(repo, [(tmpctx, ())])
            newid = prec.node()
        else:
            phases.retractboundary(repo, tr, bumped.phase(), [newid])
            obsolete.createmarkers(repo, [(tmpctx, (repo[newid],))],
                                   flag=obsolete.bumpedfix)
        bmupdate(newid)
        tr.close()
        repo.ui.status(_('committed as %s\n') % node.short(newid))
    finally:
        tr.release()
    # reroute the working copy parent to the new changeset
    repo.dirstate.beginparentchange()
    repo.dirstate.setparents(newid, node.nullid)
    repo.dirstate.endparentchange()

def _solvedivergent(ui, repo, divergent, dryrun=False, confirm=False,
                    progresscb=None):
    base, others = divergentdata(divergent)
    if len(others) > 1:
        othersstr = "[%s]" % (','.join([str(i) for i in others]))
        hint = ("changeset %d is divergent with a changeset that got splitted "
                "| into multiple ones:\n[%s]\n"
                "| This is not handled by automatic evolution yet\n"
                "| You have to fallback to manual handling with commands "
                "such as:\n"
                "| - hg touch -D\n"
                "| - hg prune\n"
                "| \n"
                "| You should contact your local evolution Guru for help.\n"
                % (divergent, othersstr))
        raise util.Abort("we do not handle divergence with split yet",
                         hint=hint)
    other = others[0]
    if divergent.phase() <= phases.public:
        raise util.Abort("we can't resolve this conflict from the public side",
                    hint="%s is public, try from %s" % (divergent, other))
    if len(other.parents()) > 1:
        raise util.Abort("divergent changeset can't be a merge (yet)",
                    hint="You have to fallback to solving this by hand...\n"
                         "| This probably means redoing the merge and using "
                         "| `hg prune` to kill older version.")
    if other.p1() not in divergent.parents():
        raise util.Abort("parents are not common (not handled yet)",
                    hint="| %(d)s, %(o)s are not based on the same changeset.\n"
                         "| With the current state of its implementation, \n"
                         "| evolve does not work in that case.\n"
                         "| rebase one of them next to the other and run \n"
                         "| this command again.\n"
                         "| - either: hg rebase --dest 'p1(%(d)s)' -r %(o)s\n"
                         "| - or:     hg rebase --dest 'p1(%(o)s)' -r %(d)s"
                              % {'d': divergent, 'o': other})

    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if not ui.quiet or confirm:
        ui.write(_('merge:'))
        displayer.show(divergent)
        ui.write(_('with: '))
        displayer.show(other)
        ui.write(_('base: '))
        displayer.show(base)
    if confirm and ui.prompt('perform evolve? [Ny]') != 'y':
        raise util.Abort(_('evolve aborted by user'))
    if dryrun:
        ui.write('hg update -c %s &&\n' % divergent)
        ui.write('hg merge %s &&\n' % other)
        ui.write('hg commit -m "auto merge resolving conflict between '
                 '%s and %s"&&\n' % (divergent, other))
        ui.write('hg up -C %s &&\n' % base)
        ui.write('hg revert --all --rev tip &&\n')
        ui.write('hg commit -m "`hg log -r %s --template={desc}`";\n'
                 % divergent)
        return
    if divergent not in repo[None].parents():
        repo.ui.status(_('updating to "local" conflict\n'))
        hg.update(repo, divergent.rev())
    repo.ui.note(_('merging divergent changeset\n'))
    if progresscb: progresscb()
    stats = merge.update(repo,
                         other.node(),
                         branchmerge=True,
                         force=False,
                         partial=None,
                         ancestor=base.node(),
                         mergeancestor=True)
    hg._showstats(repo, stats)
    if stats[3]:
        repo.ui.status(_("use 'hg resolve' to retry unresolved file merges "
                         "or 'hg update -C .' to abandon\n"))
    if stats[3] > 0:
        raise util.Abort('merge conflict between several amendments '
            '(this is not automated yet)',
            hint="""/!\ You can try:
/!\ * manual merge + resolve => new cset X
/!\ * hg up to the parent of the amended changeset (which are named W and Z)
/!\ * hg revert --all -r X
/!\ * hg ci -m "same message as the amended changeset" => new cset Y
/!\ * hg kill -n Y W Z
""")
    if progresscb: progresscb()
    tr = repo.transaction('stabilize-divergent')
    try:
        repo.dirstate.beginparentchange()
        repo.dirstate.setparents(divergent.node(), node.nullid)
        repo.dirstate.endparentchange()
        oldlen = len(repo)
        amend(ui, repo, message='', logfile='')
        if oldlen == len(repo):
            new = divergent
            # no changes
        else:
            new = repo['.']
        obsolete.createmarkers(repo, [(other, (new,))])
        phases.retractboundary(repo, tr, other.phase(), [new.node()])
        tr.close()
    finally:
        tr.release()

def divergentdata(ctx):
    """return base, other part of a conflict

    This only return the first one.

    XXX this woobly function won't survive XXX
    """
    for base in ctx._repo.set('reverse(precursors(%d))', ctx):
        newer = obsolete.successorssets(ctx._repo, base.node())
        # drop filter and solution including the original ctx
        newer = [n for n in newer if n and ctx.node() not in n]
        if newer:
            return base, tuple(ctx._repo[o] for o in newer[0])
    raise util.Abort("base of divergent changeset %s not found" % ctx,
                     hint='this case is not yet handled')



shorttemplate = '[{rev}] {desc|firstline}\n'

@command('^previous',
         [('B', 'move-bookmark', False,
             _('Move current active bookmark after update'))],
         '[-B]')
def cmdprevious(ui, repo, **opts):
    """update to parent and display summary lines"""
    wkctx = repo[None]
    wparents = wkctx.parents()
    if len(wparents) != 1:
        raise util.Abort('merge in progress')

    parents = wparents[0].parents()
    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if len(parents) == 1:
        p = parents[0]
        bm = bookmarks.readcurrent(repo)
        shouldmove = opts.get('move_bookmark') and bm is not None
        ret = hg.update(repo, p.rev())
        if not ret:
            if shouldmove:
                repo._bookmarks[bm] = p.node()
                repo._bookmarks.write()
            else:
                bookmarks.unsetcurrent(repo)
        displayer.show(p)
        return 0
    else:
        for p in parents:
            displayer.show(p)
        ui.warn(_('multiple parents, explicitly update to one\n'))
        return 1

@command('^next',
         [('B', 'move-bookmark', False,
             _('Move current active bookmark after update'))],
         '[-B]')
def cmdnext(ui, repo, **opts):
    """update to child and display summary lines"""
    wkctx = repo[None]
    wparents = wkctx.parents()
    if len(wparents) != 1:
        raise util.Abort('merge in progress')

    children = [ctx for ctx in wparents[0].children() if not ctx.obsolete()]
    displayer = cmdutil.show_changeset(ui, repo, {'template': shorttemplate})
    if not children:
        ui.warn(_('no non-obsolete children\n'))
        return 1
    if len(children) == 1:
        c = children[0]
        bm = bookmarks.readcurrent(repo)
        shouldmove = opts.get('move_bookmark') and bm is not None
        ret = hg.update(repo, c.rev())
        if not ret:
            if shouldmove:
                repo._bookmarks[bm] = c.node()
                repo._bookmarks.write()
            else:
                bookmarks.unsetcurrent(repo)
        displayer.show(c)
        return 0
    else:
        for c in children:
            displayer.show(c)
        ui.warn(_('multiple non-obsolete children, '
            'explicitly update to one of them\n'))
        return 1

def _reachablefrombookmark(repo, revs, mark):
    """filter revisions and bookmarks reachable from the given bookmark
    yoinked from mq.py
    """
    marks = repo._bookmarks
    if mark not in marks:
        raise util.Abort(_("bookmark '%s' not found") % mark)

    # If the requested bookmark is not the only one pointing to a
    # a revision we have to only delete the bookmark and not strip
    # anything. revsets cannot detect that case.
    uniquebm = True
    for m, n in marks.iteritems():
        if m != mark and n == repo[mark].node():
            uniquebm = False
            break
    if uniquebm:
        rsrevs = repo.revs("ancestors(bookmark(%s)) - "
                           "ancestors(head() and not bookmark(%s)) - "
                           "ancestors(bookmark() and not bookmark(%s)) - "
                           "obsolete()",
                           mark, mark, mark)
        revs = set(revs)
        revs.update(set(rsrevs))
        revs = sorted(revs)
    return marks, revs

def _deletebookmark(ui, marks, mark):
    del marks[mark]
    marks.write()
    ui.write(_("bookmark '%s' deleted\n") % mark)



def _getmetadata(**opts):
    metadata = {}
    date = opts.get('date')
    user = opts.get('user')
    if date:
        metadata['date'] = '%i %i' % util.parsedate(date)
    if user:
        metadata['user'] = user
    return metadata


@command('^prune|obsolete|kill',
    [('n', 'new', [], _("successor changeset (DEPRECATED)")),
     ('s', 'succ', [], _("successor changeset")),
     ('r', 'rev', [], _("revisions to prune")),
     ('', 'biject', False, _("do a 1-1 map between rev and successor ranges")),
     ('B', 'bookmark', '', _("remove revs only reachable from given"
                             " bookmark"))] + metadataopts,
    _('[OPTION] [-r] REV...'))
    # -U  --noupdate option to prevent wc update and or bookmarks update ?
def cmdprune(ui, repo, *revs, **opts):
    """hide changesets by marking them obsolete

    Obsolete changesets becomes invisible to all commands.

    Unpruned descendants of pruned changesets becomes "unstable". Use the
    :hg:`evolve` to handle such situation.

    When the working directory parent is pruned, the repository is updated to a
    non-obsolete parent.

    You can use the ``--succ`` option to inform mercurial that a newer version
    of the pruned changeset exists.

    You can use the ``--biject`` option to specify a 1-1 (bijection) between
    revisions to prune and successor changesets. This option may be removed in
    a future release (with the functionality absorbed automatically).

    """
    revs = scmutil.revrange(repo, list(revs) + opts.get('rev'))
    succs = opts['new'] + opts['succ']
    bookmark = opts.get('bookmark')
    metadata = _getmetadata(**opts)
    biject = opts.get('biject')

    if bookmark:
        marks,revs = _reachablefrombookmark(repo, revs, bookmark)
        if not revs:
            # no revisions to prune - delete bookmark immediately
            _deletebookmark(ui, marks, bookmark)

    if not revs:
        raise util.Abort(_('nothing to prune'))

    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        # defines pruned changesets
        precs = []
        revs.sort()
        for p in revs:
            cp = repo[p]
            if not cp.mutable():
                # note: createmarkers() would have raised something anyway
                raise util.Abort('cannot prune immutable changeset: %s' % cp,
                                 hint='see "hg help phases" for details')
            precs.append(cp)
        if not precs:
            raise util.Abort('nothing to prune')

        # defines successors changesets
        sucs = scmutil.revrange(repo, succs)
        sucs.sort()
        sucs = tuple(repo[n] for n in sucs)
        if not biject and len(sucs) > 1 and len(precs) > 1:
            msg = "Can't use multiple successors for multiple precursors"
            raise util.Abort(msg)

        if biject and len(sucs) != len(precs):
            msg = "Can't use %d successors for %d precursors" \
                % (len(sucs), len(precs))
            raise util.Abort(msg)

        relations = [(p, sucs) for p in precs]
        if biject:
            relations = [(p, (s,)) for p, s in zip(precs, sucs)]

        # create markers
        obsolete.createmarkers(repo, relations, metadata=metadata)

        # informs that changeset have been pruned
        ui.status(_('%i changesets pruned\n') % len(precs))

        wdp = repo['.']

        if len(sucs) == 1 and len(precs) == 1 and wdp in precs:
            # '.' killed, so update to the successor
            newnode = sucs[0]
        else:
            # update to an unkilled parent
            newnode = wdp

            while newnode.obsolete():
                newnode = newnode.parents()[0]

        if newnode.node() != wdp.node():
            commands.update(ui, repo, newnode.rev())
            ui.status(_('working directory now at %s\n') % newnode)
        # update bookmarks
        if bookmark:
            _deletebookmark(ui, marks, bookmark)
        for ctx in repo.unfiltered().set('bookmark() and %ld', precs):
            # used to be:
            #
            #   ldest = list(repo.set('max((::%d) - obsolete())', ctx))
            #   if ldest:
            #      c = ldest[0]
            #
            # but then revset took a lazy arrow in the knee and became much
            # slower. The new forms makes as much sense and a much faster.
            for dest in ctx.ancestors():
                if not dest.obsolete():
                    updatebookmarks = _bookmarksupdater(repo, ctx.node())
                    updatebookmarks(dest.node())
                    break
    finally:
        lockmod.release(lock, wlock)

@command('amend|refresh',
    [('A', 'addremove', None,
     _('mark new/missing files as added/removed before committing')),
    ('e', 'edit', False, _('invoke editor on commit messages')),
    ('', 'close-branch', None,
     _('mark a branch as closed, hiding it from the branch list')),
    ('s', 'secret', None, _('use the secret phase for committing')),
    ] + walkopts + commitopts + commitopts2 + commitopts3,
    _('[OPTION]... [FILE]...'))
def amend(ui, repo, *pats, **opts):
    """combine a changeset with updates and replace it with a new one

    Commits a new changeset incorporating both the changes to the given files
    and all the changes from the current parent changeset into the repository.

    See :hg:`commit` for details about committing changes.

    If you don't specify -m, the parent's message will be reused.

    Behind the scenes, Mercurial first commits the update as a regular child
    of the current parent. Then it creates a new commit on the parent's parents
    with the updated contents. Then it changes the working copy parent to this
    new combined changeset. Finally, the old changeset and its update are hidden
    from :hg:`log` (unless you use --hidden with log).

    Returns 0 on success, 1 if nothing changed.
    """
    opts = opts.copy()
    edit = opts.pop('edit', False)
    log = opts.get('logfile')
    opts['amend'] = True
    if not (edit or opts['message'] or log):
        opts['message'] = repo['.'].description()
    _resolveoptions(ui, opts)
    _alias, commitcmd = cmdutil.findcmd('commit', commands.table)
    return commitcmd[0](ui, repo, *pats, **opts)


def _touchedbetween(repo, source, dest, match=None):
    touched = set()
    for files in repo.status(source, dest, match=match)[:3]:
        touched.update(files)
    return touched

def _commitfiltered(repo, ctx, match, target=None):
    """Recommit ctx with changed files not in match. Return the new
    node identifier, or None if nothing changed.
    """
    base = ctx.p1()
    if target is None:
        target = base
    # ctx
    initialfiles = _touchedbetween(repo, base, ctx)
    if base == target:
        affected = set(f for f in initialfiles if match(f))
        newcontent = set()
    else:
        affected = _touchedbetween(repo, target, ctx, match=match)
        newcontent = _touchedbetween(repo, target, base, match=match)
    # The commit touchs all existing files
    # + all file that needs a new content
    # - the file affected bny uncommit with the same content than base.
    files = (initialfiles - affected) | newcontent
    if not newcontent and files == initialfiles:
        return None

    # Filter copies
    copied = copies.pathcopies(target, ctx)
    copied = dict((src, dst) for src, dst in copied.iteritems()
                  if dst in files)
    def filectxfn(repo, memctx, path, contentctx=ctx, redirect=newcontent):
        if path in redirect:
            return filectxfn(repo, memctx, path, contentctx=target, redirect=())
        if path not in contentctx:
            return None
        fctx = contentctx[path]
        flags = fctx.flags()
        mctx = memfilectx(repo, fctx.path(), fctx.data(),
                          islink='l' in flags,
                          isexec='x' in flags,
                          copied=copied.get(path))
        return mctx

    new = context.memctx(repo,
                         parents=[base.node(), node.nullid],
                         text=ctx.description(),
                         files=files,
                         filectxfn=filectxfn,
                         user=ctx.user(),
                         date=ctx.date(),
                         extra=ctx.extra())
    # commitctx always create a new revision, no need to check
    newid = repo.commitctx(new)
    return newid

def _uncommitdirstate(repo, oldctx, match):
    """Fix the dirstate after switching the working directory from
    oldctx to a copy of oldctx not containing changed files matched by
    match.
    """
    ctx = repo['.']
    ds = repo.dirstate
    copies = dict(ds.copies())
    m, a, r = repo.status(oldctx.p1(), oldctx, match=match)[:3]
    for f in m:
        if ds[f] == 'r':
            # modified + removed -> removed
            continue
        ds.normallookup(f)

    for f in a:
        if ds[f] == 'r':
            # added + removed -> unknown
            ds.drop(f)
        elif ds[f] != 'a':
            ds.add(f)

    for f in r:
        if ds[f] == 'a':
            # removed + added -> normal
            ds.normallookup(f)
        elif ds[f] != 'r':
            ds.remove(f)

    # Merge old parent and old working dir copies
    oldcopies = {}
    for f in (m + a):
        src = oldctx[f].renamed()
        if src:
            oldcopies[f] = src[0]
    oldcopies.update(copies)
    copies = dict((dst, oldcopies.get(src, src))
                  for dst, src in oldcopies.iteritems())
    # Adjust the dirstate copies
    for dst, src in copies.iteritems():
        if (src not in ctx or dst in ctx or ds[dst] != 'a'):
            src = None
        ds.copy(src, dst)

@command('^uncommit',
    [('a', 'all', None, _('uncommit all changes when no arguments given')),
     ('r', 'rev', '', _('revert commit content to REV instead')),
     ] + commands.walkopts,
    _('[OPTION]... [NAME]'))
def uncommit(ui, repo, *pats, **opts):
    """move changes from parent revision to working directory

    Changes to selected files in the checked out revision appear again as
    uncommitted changed in the working directory. A new revision
    without the selected changes is created, becomes the checked out
    revision, and obsoletes the previous one.

    The --include option specifies patterns to uncommit.
    The --exclude option specifies patterns to keep in the commit.

    The --rev argument let you change the commit file to a content of another
    revision. It still does not change the content of your file in the working
    directory.

    Return 0 if changed files are uncommitted.
    """

    wlock = lock = tr = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        wctx = repo[None]
        if len(wctx.parents()) <= 0:
            raise util.Abort(_("cannot uncommit null changeset"))
        if len(wctx.parents()) > 1:
            raise util.Abort(_("cannot uncommit while merging"))
        old = repo['.']
        if old.phase() == phases.public:
            raise util.Abort(_("cannot rewrite immutable changeset"))
        if len(old.parents()) > 1:
            raise util.Abort(_("cannot uncommit merge changeset"))
        oldphase = old.phase()
        updatebookmarks = _bookmarksupdater(repo, old.node())


        rev = None
        if opts.get('rev'):
            rev = scmutil.revsingle(repo, opts.get('rev'))
            ctx = repo[None]
            if ctx.p1() == rev or ctx.p2() == rev:
                raise util.Abort(_("cannot uncommit to parent changeset"))

        # Recommit the filtered changeset
        tr = repo.transaction('uncommit')
        newid = None
        if (pats or opts.get('include') or opts.get('exclude')
            or opts.get('all')):
            match = scmutil.match(old, pats, opts)
            newid = _commitfiltered(repo, old, match, target=rev)
        if newid is None:
            raise util.Abort(_('nothing to uncommit'),
                             hint=_("use --all to uncommit all files"))
        # Move local changes on filtered changeset
        obsolete.createmarkers(repo, [(old, (repo[newid],))])
        phases.retractboundary(repo, tr, oldphase, [newid])
        repo.dirstate.beginparentchange()
        repo.dirstate.setparents(newid, node.nullid)
        _uncommitdirstate(repo, old, match)
        repo.dirstate.endparentchange()
        updatebookmarks(newid)
        if not repo[newid].files():
            ui.warn(_("new changeset is empty\n"))
            ui.status(_('(use "hg prune ." to remove it)\n'))
        tr.close()
    finally:
        lockmod.release(tr, lock, wlock)

@eh.wrapcommand('commit')
def commitwrapper(orig, ui, repo, *arg, **kwargs):
    if kwargs.get('amend', False):
        lock = None
    else:
        lock = repo.lock()
    try:
        obsoleted = kwargs.get('obsolete', [])
        if obsoleted:
            obsoleted = repo.set('%lr', obsoleted)
        result = orig(ui, repo, *arg, **kwargs)
        if not result: # commit successed
            new = repo['-1']
            oldbookmarks = []
            markers = []
            for old in obsoleted:
                oldbookmarks.extend(repo.nodebookmarks(old.node()))
                markers.append((old, (new,)))
            if markers:
                obsolete.createmarkers(repo, markers)
            for book in oldbookmarks:
                repo._bookmarks[book] = new.node()
            if oldbookmarks:
                repo._bookmarks.write()
        return result
    finally:
        if lock is not None:
            lock.release()

@command('^touch',
    [('r', 'rev', [], 'revision to update'),
     ('D', 'duplicate', False,
      'do not mark the new revision as successor of the old one')],
    # allow to choose the seed ?
    _('[-r] revs'))
def touch(ui, repo, *revs, **opts):
    """create successors that are identical to their predecessors except for the changeset ID

    This is used to "resurrect" changesets
    """
    duplicate = opts['duplicate']
    revs = list(revs)
    revs.extend(opts['rev'])
    if not revs:
        revs = ['.']
    revs = scmutil.revrange(repo, revs)
    if not revs:
        ui.write_err('no revision to touch\n')
        return 1
    if not duplicate and repo.revs('public() and %ld', revs):
        raise util.Abort("can't touch public revision")
    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('touch')
        revs.sort() # ensure parent are run first
        newmapping = {}
        try:
            for r in revs:
                ctx = repo[r]
                extra = ctx.extra().copy()
                extra['__touch-noise__'] = random.randint(0, 0xffffffff)
                # search for touched parent
                p1 = ctx.p1().node()
                p2 = ctx.p2().node()
                p1 = newmapping.get(p1, p1)
                p2 = newmapping.get(p2, p2)
                new, unusedvariable = rewrite(repo, ctx, [], ctx,
                                              [p1, p2],
                                              commitopts={'extra': extra})
                # store touched version to help potential children
                newmapping[ctx.node()] = new
                if not duplicate:
                    obsolete.createmarkers(repo, [(ctx, (repo[new],))])
                phases.retractboundary(repo, tr, ctx.phase(), [new])
                if ctx in repo[None].parents():
                    repo.dirstate.beginparentchange()
                    repo.dirstate.setparents(new, node.nullid)
                    repo.dirstate.endparentchange()
            tr.close()
        finally:
            tr.release()
    finally:
        lockmod.release(lock, wlock)

@command('^fold|squash',
    [('r', 'rev', [], _("revision to fold")),
     ('', 'exact', None, _("only fold specified revisions"))
    ] + commitopts + commitopts2,
    _('hg fold [OPTION]... [-r] REV'))
def fold(ui, repo, *revs, **opts):
    """fold multiple revisions into a single one

    Folds a set of revisions with the parent of the working directory.
    All revisions linearly between the given revisions and the parent
    of the working directory will also be folded.

    Use --exact for folding only the specified revisions while ignoring the
    parent of the working directory. In this case, the given revisions must
    form a linear unbroken chain.

    .. container:: verbose

     Some examples:

     - Fold the current revision with its parent::

         hg fold .^

     - Fold all draft revisions with working directory parent::

         hg fold 'draft()'

       See :hg:`help phases` for more about draft revisions and
       :hg:`help revsets` for more about the `draft()` keyword

     - Fold revisions 3, 4, 5, and 6 with the working directory parent::

         hg fold 3:6

     - Only fold revisions linearly between foo and @::

         hg fold foo::@ --exact
    """
    revs = list(revs)
    revs.extend(opts['rev'])
    if not revs:
        raise util.Abort(_('no revisions specified'))

    revs = scmutil.revrange(repo, revs)

    if not opts['exact']:
        # Try to extend given revision starting from the working directory
        extrevs = repo.revs('(%ld::.) or (.::%ld)', revs, revs)
        discardedrevs = [r for r in revs if r not in extrevs]
        if discardedrevs:
            raise util.Abort(_("cannot fold non-linear revisions"),
                               hint=_("given revisions are unrelated to parent "
                                      "of working directory"))
        revs = extrevs

    if len(revs) == 1:
        ui.write_err(_('single revision specified, nothing to fold\n'))
        return 1

    roots = repo.revs('roots(%ld)', revs)
    if len(roots) > 1:
        raise util.Abort(_("cannot fold non-linear revisions "
                           "(multiple roots given)"))
    root = repo[roots.first()]
    if root.phase() <= phases.public:
        raise util.Abort(_("cannot fold public revisions"))
    heads = repo.revs('heads(%ld)', revs)
    if len(heads) > 1:
        raise util.Abort(_("cannot fold non-linear revisions "
                           "(multiple heads given)"))
    head = repo[heads.first()]
    wlock = lock = None
    try:
        wlock = repo.wlock()
        lock = repo.lock()
        tr = repo.transaction('touch')
        try:
            commitopts = opts.copy()
            allctx = [repo[r] for r in revs]
            targetphase = max(c.phase() for c in allctx)

            if commitopts.get('message') or commitopts.get('logfile'):
                commitopts['edit'] = False
            else:
                msgs = ["HG: This is a fold of %d changesets." % len(allctx)]
                msgs += ["HG: Commit message of changeset %s.\n\n%s\n" %
                         (c.rev(), c.description()) for c in allctx]
                commitopts['message'] =  "\n".join(msgs)
                commitopts['edit'] = True

            newid, unusedvariable = rewrite(repo, root, allctx, head,
                                            [root.p1().node(), root.p2().node()],
                                            commitopts=commitopts)
            phases.retractboundary(repo, tr, targetphase, [newid])
            obsolete.createmarkers(repo, [(ctx, (repo[newid],))
                                 for ctx in allctx])
            tr.close()
        finally:
            tr.release()
        ui.status('%i changesets folded\n' % len(revs))
        if repo['.'].rev() in revs:
            hg.update(repo, newid)
    finally:
        lockmod.release(lock, wlock)



@eh.wrapcommand('graft')
def graftwrapper(orig, ui, repo, *revs, **kwargs):
    kwargs = dict(kwargs)
    revs = list(revs) + kwargs.get('rev', [])
    kwargs['rev'] = []
    obsoleted = kwargs.setdefault('obsolete', [])

    lock = repo.lock()
    try:
        if kwargs.get('old_obsolete'):
            if kwargs.get('continue'):
                obsoleted.extend(repo.opener.read('graftstate').splitlines())
            else:
                obsoleted.extend(revs)
        # convert obsolete target into revs to avoid alias joke
        obsoleted[:] = [str(i) for i in repo.revs('%lr', obsoleted)]
        if obsoleted and len(revs) > 1:

            raise error.Abort(_('cannot graft multiple revisions while '
                                'obsoleting (for now).'))

        return commitwrapper(orig, ui, repo,*revs, **kwargs)
    finally:
        lock.release()

@eh.extsetup
def oldevolveextsetup(ui):
    try:
        rebase = extensions.find('rebase')
    except KeyError:
        raise error.Abort(_('evolution extension requires rebase extension.'))

    for cmd in ['kill', 'uncommit', 'touch', 'fold']:
        entry = extensions.wrapcommand(cmdtable, cmd,
                                       warnobserrors)

    entry = cmdutil.findcmd('commit', commands.table)[1]
    entry[1].append(('o', 'obsolete', [],
                     _("make commit obsolete this revision (DEPRECATED)")))
    entry = cmdutil.findcmd('graft', commands.table)[1]
    entry[1].append(('o', 'obsolete', [],
                     _("make graft obsoletes this revision (DEPRECATED)")))
    entry[1].append(('O', 'old-obsolete', False,
                     _("make graft obsoletes its source (DEPRECATED)")))

#####################################################################
### Obsolescence marker exchange experimenation                   ###
#####################################################################

def obsexcmsg(ui, message, important=False):
    verbose = ui.configbool('experimental', 'verbose-obsolescence-exchange',
                             False)
    if verbose:
        message = 'OBSEXC: ' + message
    if important or verbose:
        ui.status(message)

def obsexcprg(ui, *args, **kwargs):
    topic = 'obsmarkers exchange'
    if ui.configbool('experimental', 'verbose-obsolescence-exchange', False):
        topic = 'OBSEXC'
    ui.progress(topic, *args, **kwargs)

if getattr(exchange, '_pushdiscoveryobsmarkers', None) is not None:
    @eh.wrapfunction(exchange, '_pushdiscoveryobsmarkers')
    def _pushdiscoveryobsmarkers(orig, pushop):
        if (obsolete._enabled
            and pushop.repo.obsstore
            and 'obsolete' in pushop.remote.listkeys('namespaces')):
            repo = pushop.repo
            obsexcmsg(repo.ui, "computing relevant nodes\n")
            revs = list(repo.revs('::%ln', pushop.futureheads))
            unfi = repo.unfiltered()
            cl = unfi.changelog
            if not pushop.remote.capable('_evoext_obshash_0'):
                # do not trust core yet
                # return orig(pushop)
                nodes = [cl.node(r) for r in revs]
                if nodes:
                    obsexcmsg(repo.ui, "computing markers relevant to %i nodes\n"
                                       % len(nodes))
                    pushop.outobsmarkers = repo.obsstore.relevantmarkers(nodes)
                else:
                    obsexcmsg(repo.ui, "markers already in sync\n")
                    pushop.outobsmarkers = []
                    pushop.outobsmarkers = repo.obsstore.relevantmarkers(nodes)
                return

            common = []
            obsexcmsg(repo.ui, "looking for common markers in %i nodes\n"
                               % len(revs))
            commonrevs = list(unfi.revs('::%ln', pushop.outgoing.commonheads))
            common = findcommonobsmarkers(pushop.ui, unfi, pushop.remote, commonrevs)

            revs = list(unfi.revs('%ld - (::%ln)', revs, common))
            nodes = [cl.node(r) for r in revs]
            if nodes:
                obsexcmsg(repo.ui, "computing markers relevant to %i nodes\n"
                                   % len(nodes))
                pushop.outobsmarkers = repo.obsstore.relevantmarkers(nodes)
            else:
                obsexcmsg(repo.ui, "markers already in sync\n")
                pushop.outobsmarkers = []

@eh.wrapfunction(wireproto, 'capabilities')
def discocapabilities(orig, repo, proto):
    """wrapper to advertise new capability"""
    caps = orig(repo, proto)
    if obsolete._enabled:
        caps += ' _evoext_obshash_0'
    return caps

@eh.extsetup
def _installobsmarkersdiscovery(ui):
    hgweb_mod.perms['evoext_obshash'] = 'pull'
    # wrap command content
    oldcap, args = wireproto.commands['capabilities']
    def newcap(repo, proto):
        return discocapabilities(oldcap, repo, proto)
    wireproto.commands['capabilities'] = (newcap, args)
    wireproto.commands['evoext_obshash'] = (srv_obshash, 'nodes')
    if getattr(exchange, '_pushdiscoveryobsmarkers', None) is None:
        ui.warn('evolve: your mercurial version is too old\n'
                'evolve: (running in degraded mode, push will includes all markers)\n')
    else:
        olddisco = exchange.pushdiscoverymapping['obsmarker']
        def newdisco(pushop):
            _pushdiscoveryobsmarkers(olddisco, pushop)
        exchange.pushdiscoverymapping['obsmarker'] = newdisco

### Set discovery START

from mercurial import dagutil
from mercurial import setdiscovery

def _obshash(repo, nodes):
    hashs = _obsrelsethashtree(repo)
    nm = repo.changelog.nodemap
    revs = [nm.get(n) for n in nodes]
    return [r is None and nullid or hashs[r][1] for r in revs]

def srv_obshash(repo, proto, nodes):
    return wireproto.encodelist(_obshash(repo, wireproto.decodelist(nodes)))

@eh.addattr(localrepo.localpeer, 'evoext_obshash')
def local_obshash(peer, nodes):
    return _obshash(peer._repo, nodes)

@eh.addattr(wireproto.wirepeer, 'evoext_obshash')
def peer_obshash(self, nodes):
    d = self._call("evoext_obshash", nodes=wireproto.encodelist(nodes))
    try:
        return wireproto.decodelist(d)
    except ValueError:
        self._abort(error.ResponseError(_("unexpected response:"), d))

def findcommonobsmarkers(ui, local, remote, probeset,
                         initialsamplesize=100,
                         fullsamplesize=200):
    # from discovery
    roundtrips = 0
    cl = local.changelog
    dag = dagutil.revlogdag(cl)
    localhash = _obsrelsethashtree(local)
    missing = set()
    common = set()
    undecided = set(probeset)
    _takefullsample = setdiscovery._takefullsample

    while undecided:

        ui.note(_("sampling from both directions\n"))
        sample = _takefullsample(dag, undecided, size=fullsamplesize)

        roundtrips += 1
        ui.debug("query %i; still undecided: %i, sample size is: %i\n"
                 % (roundtrips, len(undecided), len(sample)))
        # indices between sample and externalized version must match
        sample = list(sample)
        remotehash = remote.evoext_obshash(dag.externalizeall(sample))

        yesno = [localhash[ix][1] == remotehash[si]
                 for si, ix in enumerate(sample)]

        commoninsample = set(n for i, n in enumerate(sample) if yesno[i])
        common.update(dag.ancestorset(commoninsample, common))

        missinginsample = [n for i, n in enumerate(sample) if not yesno[i]]
        missing.update(dag.descendantset(missinginsample, missing))

        undecided.difference_update(missing)
        undecided.difference_update(common)


    result = dag.headsetofconnecteds(common)
    ui.debug("%d total queries\n" % roundtrips)

    if not result:
        return set([nullid])
    return dag.externalizeall(result)


_pushkeyescape = getattr(obsolete, '_pushkeyescape', None)

class pushobsmarkerStringIO(StringIO):
    """hacky string io for progress"""

    @util.propertycache
    def length(self):
        return len(self.getvalue())

    def read(self, size=None):
        obsexcprg(self.ui, self.tell(), unit="bytes", total=self.length)
        return StringIO.read(self, size)

    def __iter__(self):
        d = self.read(4096)
        while d:
            yield d
            d = self.read(4096)

@eh.wrapfunction(exchange, '_pushobsolete')
def _pushobsolete(orig, pushop):
    """utility function to push obsolete markers to a remote"""
    stepsdone = getattr(pushop, 'stepsdone', None)
    if stepsdone is not None:
        if 'obsmarkers' in stepsdone:
            return
        stepsdone.add('obsmarkers')
    if util.safehasattr(pushop, 'cgresult'):
        cgresult = pushop.cgresult
    else:
        cgresult = pushop.ret
    if cgresult == 0:
        return
    pushop.ui.debug('try to push obsolete markers to remote\n')
    repo = pushop.repo
    remote = pushop.remote
    unfi = repo.unfiltered()
    cl = unfi.changelog
    if (obsolete._enabled and repo.obsstore and
        'obsolete' in remote.listkeys('namespaces')):
        markers = pushop.outobsmarkers
        if not markers:
            obsexcmsg(repo.ui, "no marker to push\n")
        elif remote.capable('_evoext_pushobsmarkers_0'):
            obsdata = pushobsmarkerStringIO()
            for chunk in obsolete.encodemarkers(markers, True):
                obsdata.write(chunk)
            obsdata.seek(0)
            obsdata.ui = repo.ui
            obsexcmsg(repo.ui, "pushing %i obsolescence markers (%i bytes)\n"
                               % (len(markers), len(obsdata.getvalue())),
                      True)
            remote.evoext_pushobsmarkers_0(obsdata)
            obsexcprg(repo.ui, None)
        else:
            rslts = []
            remotedata = _pushkeyescape(markers).items()
            totalbytes = sum(len(d) for k,d in remotedata)
            sentbytes = 0
            obsexcmsg(repo.ui, "pushing %i obsolescence markers in %i pushkey payload (%i bytes)\n"
                                % (len(markers), len(remotedata), totalbytes),
                      True)
            for key, data in remotedata:
                obsexcprg(repo.ui, sentbytes, item=key, unit="bytes",
                          total=totalbytes)
                rslts.append(remote.pushkey('obsolete', key, '', data))
                sentbytes += len(data)
                obsexcprg(repo.ui, sentbytes, item=key, unit="bytes",
                          total=totalbytes)
            obsexcprg(repo.ui, None)
            if [r for r in rslts if not r]:
                msg = _('failed to push some obsolete markers!\n')
                repo.ui.warn(msg)
        obsexcmsg(repo.ui, "DONE\n")


@eh.addattr(wireproto.wirepeer, 'evoext_pushobsmarkers_0')
def client_pushobsmarkers(self, obsfile):
    """wireprotocol peer method"""
    self.requirecap('_evoext_pushobsmarkers_0',
                    _('push obsolete markers faster'))
    ret, output = self._callpush('evoext_pushobsmarkers_0', obsfile)
    for l in output.splitlines(True):
        self.ui.status(_('remote: '), l)
    return ret

@eh.addattr(httppeer.httppeer, 'evoext_pushobsmarkers_0')
def httpclient_pushobsmarkers(self, obsfile):
    """httpprotocol peer method
    (Cannot simply use _callpush as http is doing some special handling)"""
    self.requirecap('_evoext_pushobsmarkers_0',
                    _('push obsolete markers faster'))
    ret, output = self._call('evoext_pushobsmarkers_0', data=obsfile)
    for l in output.splitlines(True):
        if l.strip():
            self.ui.status(_('remote: '), l)
    return ret

@eh.wrapfunction(localrepo.localrepository, '_restrictcapabilities')
def local_pushobsmarker_capabilities(orig, repo, caps):
    caps = orig(repo, caps)
    caps.add('_evoext_pushobsmarkers_0')
    return caps

@eh.addattr(localrepo.localpeer, 'evoext_pushobsmarkers_0')
def local_pushobsmarkers(peer, obsfile):
    data = obsfile.read()
    lock = peer._repo.lock()
    try:
        tr = peer._repo.transaction('pushkey: obsolete markers')
        try:
            new = peer._repo.obsstore.mergemarkers(tr, data)
            if new is not None:
                obsexcmsg(peer._repo.ui, "%i obsolescence markers added\n" % new, True)
            tr.close()
        finally:
            tr.release()
    finally:
        lock.release()
    peer._repo.hook('evolve_pushobsmarkers')

def srv_pushobsmarkers(repo, proto):
    """wireprotocol command"""
    fp = StringIO()
    proto.redirect()
    proto.getfile(fp)
    data = fp.getvalue()
    fp.close()
    lock = repo.lock()
    try:
        tr = repo.transaction('pushkey: obsolete markers')
        try:
            new = repo.obsstore.mergemarkers(tr, data)
            if new is not None:
                obsexcmsg(repo.ui, "%i obsolescence markers added\n" % new, True)
            tr.close()
        finally:
            tr.release()
    finally:
        lock.release()
    repo.hook('evolve_pushobsmarkers')
    return wireproto.pushres(0)

def _buildpullobsmarkersboundaries(pullop):
    """small funtion returning the argument for pull markers call
    may to contains 'heads' and 'common'. skip the key for None.

    Its a separed functio to play around with strategy for that."""
    repo = pullop.repo
    cl = pullop.repo.changelog
    remote = pullop.remote
    unfi = repo.unfiltered()
    revs = unfi.revs('::%ln', pullop.common)
    common = [nullid]
    if remote.capable('_evoext_obshash_0'):
        obsexcmsg(repo.ui, "looking for common markers in %i nodes\n"
                           % len(revs))
        common = findcommonobsmarkers(repo.ui, repo, remote, revs)
    return {'heads': pullop.pulledsubset, 'common': common}

@eh.uisetup
def addgetbundleargs(self):
    gboptsmap['evo_obscommon'] = 'nodes'

@eh.wrapfunction(exchange, '_pullbundle2extraprepare')
def _addobscommontob2pull(orig, pullop, kwargs):
    ret = orig(pullop, kwargs)
    if 'obsmarkers' in kwargs and pullop.remote.capable('_evoext_getbundle_obscommon'):
        boundaries = _buildpullobsmarkersboundaries(pullop)
        common = boundaries['common']
        if common != [nullid]:
            kwargs['evo_obscommon'] = common
    return ret

if getattr(exchange, '_getbundleobsmarkerpart', None) is not None:
    @eh.wrapfunction(exchange, '_getbundleobsmarkerpart')
    def _getbundleobsmarkerpart(orig, bundler, repo, source, heads=None, common=None,
                                bundlecaps=None, **kwargs):
        if 'evo_obscommon' not in kwargs:
            return orig(bundler, repo, source, heads, common, bundlecaps, **kwargs)

        if kwargs.get('obsmarkers', False):
            if heads is None:
                heads = repo.heads()
            obscommon = kwargs.get('evo_obscommon', ())
            obsset = repo.set('::%ln - ::%ln', heads, obscommon)
            subset = [c.node() for c in obsset]
            markers = repo.obsstore.relevantmarkers(subset)
            exchange.buildobsmarkerspart(bundler, markers)


@eh.wrapfunction(exchange, '_pullobsolete')
def _pullobsolete(orig, pullop):
    if not obsolete._enabled:
        return None
    if 'obsmarkers' not in getattr(pullop, 'todosteps', ['obsmarkers']):
        return None
    if 'obsmarkers' in getattr(pullop, 'stepsdone', []):
        return None
    wirepull = pullop.remote.capable('_evoext_pullobsmarkers_0')
    if not wirepull:
        return orig(pullop)
    if 'obsolete' not in pullop.remote.listkeys('namespaces'):
        return None # remote opted out of obsolescence marker exchange
    tr = None
    ui = pullop.repo.ui
    boundaries = _buildpullobsmarkersboundaries(pullop)
    if not set(boundaries['heads']) - set(boundaries['common']):
        obsexcmsg(ui, "nothing to pull\n")
        return None

    obsexcmsg(ui, "pull obsolescence markers\n", True)
    new = 0

    if wirepull:
        obsdata = pullop.remote.evoext_pullobsmarkers_0(**boundaries)
        obsdata = obsdata.read()
        if len(obsdata) > 5:
            obsexcmsg(ui, "merging obsolescence markers (%i bytes)\n"
                           % len(obsdata))
            tr = pullop.gettransaction()
            old = len(pullop.repo.obsstore._all)
            pullop.repo.obsstore.mergemarkers(tr, obsdata)
            new = len(pullop.repo.obsstore._all) - old
            obsexcmsg(ui, "%i obsolescence markers added\n" % new, True)
        else:
            obsexcmsg(ui, "no unknown remote markers\n")
        obsexcmsg(ui, "DONE\n")
    if new:
        pullop.repo.invalidatevolatilesets()
    return tr

def _getobsmarkersstream(repo, heads=None, common=None):
    revset = ''
    args = []
    repo = repo.unfiltered()
    if heads is None:
        revset = 'all()'
    elif heads:
        revset += "(::%ln)"
        args.append(heads)
    else:
        assert False, 'pulling no heads?'
    if common:
        revset += ' - (::%ln)'
        args.append(common)
    nodes = [c.node() for c in repo.set(revset, *args)]
    markers = repo.obsstore.relevantmarkers(nodes)
    obsdata = StringIO()
    for chunk in obsolete.encodemarkers(markers, True):
        obsdata.write(chunk)
    obsdata.seek(0)
    return obsdata

@eh.addattr(wireproto.wirepeer, 'evoext_pullobsmarkers_0')
def client_pullobsmarkers(self, heads=None, common=None):
    self.requirecap('_evoext_pullobsmarkers_0', _('look up remote obsmarkers'))
    opts = {}
    if heads is not None:
        opts['heads'] = wireproto.encodelist(heads)
    if common is not None:
        opts['common'] = wireproto.encodelist(common)
    if util.safehasattr(self, '_callcompressable'):
        f = self._callcompressable("evoext_pullobsmarkers_0", **opts)
    else:
        f = self._callstream("evoext_pullobsmarkers_0", **opts)
        f = self._decompress(f)
    length = int(f.read(20))
    chunk = 4096
    current = 0
    data = StringIO()
    ui = self.ui
    obsexcprg(ui, current, unit="bytes", total=length)
    while current < length:
        readsize = min(length-current, chunk)
        data.write(f.read(readsize))
        current += readsize
        obsexcprg(ui, current, unit="bytes", total=length)
    obsexcprg(ui, None)
    data.seek(0)
    return data

@eh.addattr(localrepo.localpeer, 'evoext_pullobsmarkers_0')
def local_pullobsmarkers(self, heads=None, common=None):
    return _getobsmarkersstream(self._repo, heads=heads, common=common)

def srv_pullobsmarkers(repo, proto, others):
    opts = wireproto.options('', ['heads', 'common'], others)
    for k, v in opts.iteritems():
        if k in ('heads', 'common'):
            opts[k] = wireproto.decodelist(v)
    obsdata = _getobsmarkersstream(repo, **opts)
    finaldata = StringIO()
    obsdata = obsdata.getvalue()
    finaldata.write('%20i' % len(obsdata))
    finaldata.write(obsdata)
    finaldata.seek(0)
    return wireproto.streamres(proto.groupchunks(finaldata))

def _obsrelsethashtree(repo):
    cache = []
    unfi = repo.unfiltered()
    for i in unfi:
        ctx = unfi[i]
        entry = 0
        sha = util.sha1()
        # add data from p1
        for p in ctx.parents():
            p = p.rev()
            if p < 0:
                p = nullid
            else:
                p = cache[p][1]
            if p != nullid:
                entry += 1
                sha.update(p)
        tmarkers = repo.obsstore.relevantmarkers([ctx.node()])
        if tmarkers:
            bmarkers = [obsolete._fm0encodeonemarker(m) for m in tmarkers]
            bmarkers.sort()
            for m in bmarkers:
                entry += 1
                sha.update(m)
        if entry:
            cache.append((ctx.node(), sha.digest()))
        else:
            cache.append((ctx.node(), nullid))
    return cache

@command('debugobsrelsethashtree',
        [] , _(''))
def debugobsrelsethashtree(ui, repo):
    """display Obsolete markers, Relevant Set, Hash Tree
    changeset-node obsrelsethashtree-node

    It computed form the "orsht" of its parent and markers
    relevant to the changeset itself."""
    for chg, obs in _obsrelsethashtree(repo):
        ui.status('%s %s\n' % (node.hex(chg), node.hex(obs)))


@eh.wrapfunction(wireproto, 'capabilities')
def capabilities(orig, repo, proto):
    """wrapper to advertise new capability"""
    caps = orig(repo, proto)
    if obsolete._enabled:
        caps += ' _evoext_pushobsmarkers_0'
        caps += ' _evoext_pullobsmarkers_0'
        caps += ' _evoext_obshash_0'
        caps += ' _evoext_getbundle_obscommon'
    return caps


@eh.extsetup
def _installwireprotocol(ui):
    localrepo.moderncaps.add('_evoext_pullobsmarkers_0')
    hgweb_mod.perms['evoext_pushobsmarkers_0'] = 'push'
    hgweb_mod.perms['evoext_pullobsmarkers_0'] = 'pull'
    wireproto.commands['evoext_pushobsmarkers_0'] = (srv_pushobsmarkers, '')
    wireproto.commands['evoext_pullobsmarkers_0'] = (srv_pullobsmarkers, '*')
    # wrap command content
    oldcap, args = wireproto.commands['capabilities']
    def newcap(repo, proto):
        return capabilities(oldcap, repo, proto)
    wireproto.commands['capabilities'] = (newcap, args)