mercurial/txnutil.py

rebase: allow rebase even if some revisions need no rebase (BC) (issue5422)

This allows you to do e.g. "hg rebase -d @ -r 'draft()'" even if some
drafts are already based off of @. You'd still need to exclude
obsolete and troubled revisions, though. We will deal with those cases
later.

Implemented by treating state[rev]==rev as "no need to rebase". I
considered adding another fake revision number like revdone=-6. That
would make the code clearer in a few places, but would add extra code
in other places.

I moved the existing test out of test-rebase-base.t and into a new
file and added more tests there, since not all are using --base.

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

from . import (
    encoding,
)

def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get('HG_PENDING')

def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)