tests/test-rebase-backup.t

revlog: add a C implementation of `headrevsdiff`

Python implementation of `headrevsdiff` can be very slow in the worst
case compared with the `heads` computation it replaces, since the
latter is done in C.

Even the average case of this Python implementation is still
noticeable in the profiles.

This patch makes the computation much much faster by doing it in C.

  $ cat << EOF >> $HGRCPATH
  > [extensions]
  > rebase=
  > EOF

==================================
Test backup-bundle config option |
==================================
Test with Pre-obsmarker rebase:
1) When config option is not set:
  $ hg init repo1
  $ cd repo1
  $ echo a>a
  $ hg ci -qAma
  $ echo b>b
  $ hg ci -qAmb
  $ echo c>c
  $ hg ci -qAmc
  $ hg up 0 -q
  $ echo d>d
  $ hg ci -qAmd
  $ echo e>e
  $ hg ci -qAme
  $ hg log -GT "{rev}: {firstline(desc)}\n"
  @  4: e
  |
  o  3: d
  |
  | o  2: c
  | |
  | o  1: b
  |/
  o  0: a
  
  $ hg rebase -s 1 -d .
  rebasing 1:d2ae7f538514 "b"
  rebasing 2:177f92b77385 "c"
  saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/d2ae7f538514-c7ed7a78-rebase.hg
  $ hg log -GT "{rev}: {firstline(desc)}\n"
  o  4: c
  |
  o  3: b
  |
  @  2: e
  |
  o  1: d
  |
  o  0: a
  

2) When config option is set:
  $ cat << EOF >> $HGRCPATH
  > [rewrite]
  > backup-bundle = False
  > EOF

  $ echo f>f
  $ hg ci -Aqmf
  $ echo g>g
  $ hg ci -Aqmg
  $ hg log -GT "{rev}: {firstline(desc)}\n"
  @  6: g
  |
  o  5: f
  |
  | o  4: c
  | |
  | o  3: b
  |/
  o  2: e
  |
  o  1: d
  |
  o  0: a
  
  $ hg rebase -s 3 -d .
  rebasing 3:05bff2a95b12 "b"
  rebasing 4:1762bde4404d "c"

  $ hg log -GT "{rev}: {firstline(desc)}\n"
  o  6: c
  |
  o  5: b
  |
  @  4: g
  |
  o  3: f
  |
  o  2: e
  |
  o  1: d
  |
  o  0: a
  
Test when rebased revisions are stripped during abort:
======================================================

  $ echo conflict > c
  $ hg ci -Am "conflict with c"
  adding c
  created new head
  $ hg log -GT "{rev}: {firstline(desc)}\n"
  @  7: conflict with c
  |
  | o  6: c
  | |
  | o  5: b
  |/
  o  4: g
  |
  o  3: f
  |
  o  2: e
  |
  o  1: d
  |
  o  0: a
  
When backup-bundle = True:
  $ cat << EOF >> $HGRCPATH
  > [rewrite]
  > backup-bundle = True
  > EOF
  $ hg rebase -s 5 -d .
  rebasing 5:1f8148a544ee "b"
  rebasing 6:f8bc7d28e573 "c"
  merging c
  warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]
  $ hg rebase --abort
  saved backup bundle to $TESTTMP/repo1/.hg/strip-backup/818c1a43c916-2b644d96-backup.hg
  rebase aborted

When backup-bundle = False:
  $ cat << EOF >> $HGRCPATH
  > [rewrite]
  > backup-bundle = False
  > EOF
  $ hg rebase -s 5 -d .
  rebasing 5:1f8148a544ee "b"
  rebasing 6:f8bc7d28e573 "c"
  merging c
  warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]
  $ hg rebase --abort
  rebase aborted
  $ cd ..