merge: deprecate accessing update results by index Now that we have named attributes, let's convert the code base to use them. We also add deprecation warnings so legacy consumers are aware of their transgressions. ``stats.unresolvedcount`` is much easier to read than ``stats[3]``, don't you think? Differential Revision: https://phab.mercurial-scm.org/D2694

procutil: introduce context-manager interface for protect/restorestdio The code looks slightly cleaner since it was pretty easy to pass arguments in wrong order.

procutil: move protectio/restoreio from commandserver Some variants of this will be useful for stdio-based servers such as sshserver.

commandserver: rewrite protectio/restoreio to not depend on ui Prepares for porting to utils.procutil, in which ui shouldn't be known. ui.flush() is replaced with ui.fout.flush() since ui.ferr wasn't involved.

util: deprecate procutil proxy functions (API) Several functions are re-exported by utils.procutil, which require explicit modname parameter. .. api:: Utility functions related to process/executable management have been moved to utils.procutil module.

procutil: bulk-replace function calls to point to new module

procutil: bulk-replace util.std* to point to new module

procutil: move process/executable management functions to new module std* files, pipe helpers, and findexe()s are moved as well since they are likely to be used with sub processes.

util: stop using readfile() in tempfilter() To unblock code move to utils.*. It's merely two lines of very Pythonic code. No helper function should be needed.

util: mark filtertable as private constant Prepares for porting to utils.*.

util: mark platform-specific gethgcmd() as private util.hgcmd() is the public interface for gethgcmd().

test-pathconflicts-merge: stop requiring symlink support The errors from the last time I took a shot at this back in early November have disappeared, so let's just enable this.

commands: use constants for merge things We have nice constants now. Let's use them to make the code easier to reason about. Differential Revision: https://phab.mercurial-scm.org/D2702

merge: use constants for actions We finish up establishing named constants in this file with actions. I remember scratching my head trying to figure out what this code was doing as part of addressing a recent security issue with subrepos. Having the named constants in place definitely makes things easier to read. I'm not convinced the new constants have the best names (I'm not an expert in this code). But they can be changed easily enough. Also, since these constants are internal only, we might want to change their values to something more human readable to facilitate debugging. Or maybe we could employ an enum type some day... Differential Revision: https://phab.mercurial-scm.org/D2701

merge: use constants for merge record state Named constants are easier to read than short string values. Differential Revision: https://phab.mercurial-scm.org/D2700

merge: use constants for merge driver state Named constants are superior to magic values. Differential Revision: https://phab.mercurial-scm.org/D2699

merge: use constants for merge state record types merge.py is using multiple discrete sets of 1 and 2 letter constants to define types and behavior. To the uninitiated, the code is very difficult to reason about. I didn't even realize there were multiple sets of constants in play initially! We begin our sanity injection with merge state records. The record types (which are serialized to disk) are now defined in RECORD_* constants. Differential Revision: https://phab.mercurial-scm.org/D2698

histedit: always define update results Before, we had a branch that could return None for the update stats. Let's just return an updateresult instance instead. Differential Revision: https://phab.mercurial-scm.org/D2693

merge: return an attrs class from update() and applyupdates() Previously, we returned a tuple containing counts. The result of an update is kind of complex and the use of tuples with nameless fields made the code a bit harder to read and constrained future expansion of the return value. Let's invent an attrs-defined class for representing the result of an update operation. We provide __getitem__ and __len__ implementations for backwards compatibility as a container type to minimize code churn. In (at least) Python 2, the % operator seems to insist on using tuples. So we had to update a consumer using the % operator. .. api:: merge.update() and merge.applyupdates() now return a class with named attributes instead of a tuple. Switch consumers to access elements by name instead of by offset. Differential Revision: https://phab.mercurial-scm.org/D2692

histedit: make histedit's commands accept revsets (issue5746) Earlier the code was only looking for rulehashes and neglecting all other revision identifiers, this code intercepts the fromrule function and calls scmutil.revsingle() on anything that is not a rulehash and then obtains the rulehash from the changectx object returned, rest of the pipeline follows as it was Differential Revision: https://phab.mercurial-scm.org/D2394

formatter: make 'originalnode' a thing in log-like templates mapping['node'] doesn't work since {node} is computed dynamically in non-web templates.

formatter: port handling of 'originalnode' to populatemap() hook This isn't a pure templating business, so let's move out of the templater module. Note that this works only in web templates where mapping['node'] is a static value.

templater: switch 'revcache' based on new mapping items It was pretty easy to leave a stale 'revcache' when switching 'ctx'. Let's make it be automatically replaced.

templater: add hook point to populate additional mapping items The 'revcache' dict will be inserted by this hook.