tests/test-merge-revert.t

wrapfunction: use functools.partial if possible

Every `extensions.bind` call inserts a frame in traceback:

   ... in closure
     return func(*(args + a), **kw)

which makes traceback noisy.

The Python stdlib has a `functools.partial` which is backed by C code and
does not pollute traceback. However it does not support instancemethod and
sets `args` attribute which could be problematic for alias handling.

This patch makes `wrapfunction` use `functools.partial` if we are wrapping a
function directly exported by a module (so it's impossible to be a class or
instance method), and special handles `wrapfunction` results so alias
handling code could handle `args` just fine.

As an example, `hg rebase -s . -d . --traceback` got 6 lines removed in my
setup:

   File "hg/mercurial/dispatch.py", line 898, in _dispatch
     cmdpats, cmdoptions)
  -File "hg/mercurial/extensions.py", line 333, in closure
  -  return func(*(args + a), **kw)
   File "hg/hgext/journal.py", line 84, in runcommand
     return orig(lui, repo, cmd, fullargs, *args)
  -File "hg/mercurial/extensions.py", line 333, in closure
  -  return func(*(args + a), **kw)
   File "fb-hgext/hgext3rd/fbamend/hiddenoverride.py", line 119, in runcommand
     result = orig(lui, repo, cmd, fullargs, *args)
   File "hg/mercurial/dispatch.py", line 660, in runcommand
     ret = _runcommand(ui, options, cmd, d)
  -File "hg/mercurial/extensions.py", line 333, in closure
  -  return func(*(args + a), **kw)
   File "hg/hgext/pager.py", line 69, in pagecmd
     return orig(ui, options, cmd, cmdfunc)
   ....

Differential Revision: https://phab.mercurial-scm.org/D632

  $ hg init

  $ echo "added file1" > file1
  $ echo "added file2" > file2
  $ hg add file1 file2
  $ hg commit -m "added file1 and file2"

  $ echo "changed file1" >> file1
  $ hg commit -m "changed file1"

  $ hg -q log
  1:08a16e8e4408
  0:d29c767a4b52
  $ hg id
  08a16e8e4408 tip

  $ hg update -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id
  d29c767a4b52
  $ echo "changed file1" >> file1
  $ hg id
  d29c767a4b52+

  $ hg revert --all
  reverting file1
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  d29c767a4b52

  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  08a16e8e4408 tip

  $ hg update -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "changed file1" >> file1

  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  08a16e8e4408 tip

  $ hg revert --all
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  08a16e8e4408 tip

  $ hg revert -r tip --all
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  08a16e8e4408 tip

  $ hg update -C
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  08a16e8e4408 tip