tests/test-rebase-partial.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

Tests rebasing with part of the rebase set already in the
destination (issue5422)

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > drawdag=$TESTDIR/drawdag.py
  > 
  > [experimental]
  > stabilization=createmarkers,allowunstable
  > 
  > [alias]
  > tglog = log -G --template "{rev}: {desc}"
  > EOF

  $ rebasewithdag() {
  >   N=`$PYTHON -c "print($N+1)"`
  >   hg init repo$N && cd repo$N
  >   hg debugdrawdag
  >   hg rebase "$@" > _rebasetmp
  >   r=$?
  >   grep -v 'saved backup bundle' _rebasetmp
  >   [ $r -eq 0 ] && hg tglog
  >   cd ..
  >   return $r
  > }

Rebase two commits, of which one is already in the right place

  $ rebasewithdag -r C+D -d B <<EOF
  > C
  > |
  > B D
  > |/
  > A
  > EOF
  rebasing 2:b18e25de2cf5 "D" (D)
  already rebased 3:26805aba1e60 "C" (C tip)
  o  4: D
  |
  | o  3: C
  |/
  | x  2: D
  | |
  o |  1: B
  |/
  o  0: A
  
Can collapse commits even if one is already in the right place

  $ rebasewithdag --collapse -r C+D -d B <<EOF
  > C
  > |
  > B D
  > |/
  > A
  > EOF
  rebasing 2:b18e25de2cf5 "D" (D)
  rebasing 3:26805aba1e60 "C" (C tip)
  o  4: Collapsed revision
  |  * D
  |  * C
  | x  3: C
  |/
  | x  2: D
  | |
  o |  1: B
  |/
  o  0: A
  
Rebase with "holes". The commits after the hole should end up on the parent of
the hole (B below), not on top of the destination (A).

  $ rebasewithdag -r B+D -d A <<EOF
  > D
  > |
  > C
  > |
  > B
  > |
  > A
  > EOF
  already rebased 1:112478962961 "B" (B)
  rebasing 3:f585351a92f8 "D" (D tip)
  o  4: D
  |
  | x  3: D
  | |
  | o  2: C
  |/
  o  1: B
  |
  o  0: A