annotate tests/test-rebase-scenario-global.t @ 32383:f928d53b687c stable

dispatch: setup color before pager for correct console information on windows

Before this patch, "hg CMD --pager on" on Windows shows output
unintentionally decorated with ANSI color escape sequences, if color
mode is "auto". This issue occurs in steps below.

  1. dispatch() invokes ui.pager() at detection of "--pager on"
  2. stdout of hg process is redirected into stdin of pager process
  3. "ui.formatted" = True, because isatty(stdout) is so before (2)
  4. color module is loaded for colorization
  5. color.w32effects = None, because GetConsoleScreenBufferInfo()
     fails on stdout redirected at (2)
  6. "ansi" color mode is chosen, because of "not w32effects"
  7. output is colorized in "ansi" mode because of "ui.formatted" = True

Even if "ansi" color mode is chosen, ordinarily redirected stdout
makes ui.formatted() return False, and colorization is avoided. But in
this issue case, "ui.formatted" = True at (3) forces output to be
colorized.

For correct console information on win32, it is needed to ensure that
color module is loaded before redirection of stdout for pagination.

BTW, if any of enabled extensions has "colortable" attribute, this
issue is avoided even before this patch, because color module is
imported as a part of loading such extension, and extension loading
occurs before setting up pager. For example, mq and keyword have
"colortable".

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: '{desc}' {branches}\n"
  > EOF


  $ hg init a
  $ cd a
  $ hg unbundle "$TESTDIR/bundles/rebase.hg"
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 7 files (+2 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..


Rebasing
D onto H - simple rebase:
(this also tests that editor is invoked if '--edit' is specified, and that we
can abort or warn for colliding untracked files)

  $ hg clone -q -u . a a1
  $ cd a1

  $ hg tglog
  @  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  

  $ hg status --rev "3^1" --rev 3
  A D
  $ echo collide > D
  $ HGEDITOR=cat hg rebase -s 3 -d 7 --edit --config merge.checkunknown=warn
  rebasing 3:32af7686d403 "D"
  D: replacing untracked file
  D
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: Nicolas Dumazet <[e-mail]>
  HG: branch 'default'
  HG: added D
  saved backup bundle to $TESTTMP/a1/.hg/strip-backup/32af7686d403-6f7dface-backup.hg (glob)
  $ cat D.orig
  collide
  $ rm D.orig

  $ hg tglog
  o  7: 'D'
  |
  @  6: 'H'
  |
  | o  5: 'G'
  |/|
  o |  4: 'F'
  | |
  | o  3: 'E'
  |/
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


D onto F - intermediate point:
(this also tests that editor is not invoked if '--edit' is not specified, and
that we can ignore for colliding untracked files)

  $ hg clone -q -u . a a2
  $ cd a2
  $ echo collide > D

  $ HGEDITOR=cat hg rebase -s 3 -d 5 --config merge.checkunknown=ignore
  rebasing 3:32af7686d403 "D"
  saved backup bundle to $TESTTMP/a2/.hg/strip-backup/32af7686d403-6f7dface-backup.hg (glob)
  $ cat D.orig
  collide
  $ rm D.orig

  $ hg tglog
  o  7: 'D'
  |
  | @  6: 'H'
  |/
  | o  5: 'G'
  |/|
  o |  4: 'F'
  | |
  | o  3: 'E'
  |/
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


E onto H - skip of G:
(this also tests that we can overwrite untracked files and don't create backups
if they have the same contents)

  $ hg clone -q -u . a a3
  $ cd a3
  $ hg cat -r 4 E | tee E
  E

  $ hg rebase -s 4 -d 7
  rebasing 4:9520eea781bc "E"
  rebasing 6:eea13746799a "G"
  note: rebase of 6:eea13746799a created no changes to commit
  saved backup bundle to $TESTTMP/a3/.hg/strip-backup/9520eea781bc-fcd8edd4-backup.hg (glob)
  $ f E.orig
  E.orig: file not found

  $ hg tglog
  o  6: 'E'
  |
  @  5: 'H'
  |
  o  4: 'F'
  |
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


F onto E - rebase of a branching point (skip G):

  $ hg clone -q -u . a a4
  $ cd a4

  $ hg rebase -s 5 -d 4
  rebasing 5:24b6387c8c8c "F"
  rebasing 6:eea13746799a "G"
  note: rebase of 6:eea13746799a created no changes to commit
  rebasing 7:02de42196ebe "H" (tip)
  saved backup bundle to $TESTTMP/a4/.hg/strip-backup/24b6387c8c8c-c3fe765d-backup.hg (glob)

  $ hg tglog
  @  6: 'H'
  |
  o  5: 'F'
  |
  o  4: 'E'
  |
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


G onto H - merged revision having a parent in ancestors of target:

  $ hg clone -q -u . a a5
  $ cd a5

  $ hg rebase -s 6 -d 7
  rebasing 6:eea13746799a "G"
  saved backup bundle to $TESTTMP/a5/.hg/strip-backup/eea13746799a-883828ed-backup.hg (glob)

  $ hg tglog
  o    7: 'G'
  |\
  | @  6: 'H'
  | |
  | o  5: 'F'
  | |
  o |  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


F onto B - G maintains E as parent:

  $ hg clone -q -u . a a6
  $ cd a6

  $ hg rebase -s 5 -d 1
  rebasing 5:24b6387c8c8c "F"
  rebasing 6:eea13746799a "G"
  rebasing 7:02de42196ebe "H" (tip)
  saved backup bundle to $TESTTMP/a6/.hg/strip-backup/24b6387c8c8c-c3fe765d-backup.hg (glob)

  $ hg tglog
  @  7: 'H'
  |
  | o  6: 'G'
  |/|
  o |  5: 'F'
  | |
  | o  4: 'E'
  | |
  | | o  3: 'D'
  | | |
  +---o  2: 'C'
  | |
  o |  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


These will fail (using --source):

G onto F - rebase onto an ancestor:

  $ hg clone -q -u . a a7
  $ cd a7

  $ hg rebase -s 6 -d 5
  nothing to rebase
  [1]

F onto G - rebase onto a descendant:

  $ hg rebase -s 5 -d 6
  abort: source is ancestor of destination
  [255]

G onto B - merge revision with both parents not in ancestors of target:

  $ hg rebase -s 6 -d 1
  rebasing 6:eea13746799a "G"
  transaction abort!
  rollback completed
  abort: cannot use revision 6 as base, result would have 3 parents
  [255]
  $ hg rebase --abort
  rebase aborted

These will abort gracefully (using --base):

G onto G - rebase onto same changeset:

  $ hg rebase -b 6 -d 6
  nothing to rebase - eea13746799a is both "base" and destination
  [1]

G onto F - rebase onto an ancestor:

  $ hg rebase -b 6 -d 5
  nothing to rebase
  [1]

F onto G - rebase onto a descendant:

  $ hg rebase -b 5 -d 6
  nothing to rebase - "base" 24b6387c8c8c is already an ancestor of destination eea13746799a
  [1]

C onto A - rebase onto an ancestor:

  $ hg rebase -d 0 -s 2
  rebasing 2:5fddd98957c8 "C"
  rebasing 3:32af7686d403 "D"
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/5fddd98957c8-f9244fa1-backup.hg (glob)
  $ hg tglog
  o  7: 'D'
  |
  o  6: 'C'
  |
  | @  5: 'H'
  | |
  | | o  4: 'G'
  | |/|
  | o |  3: 'F'
  |/ /
  | o  2: 'E'
  |/
  | o  1: 'B'
  |/
  o  0: 'A'
  

Check rebasing public changeset

  $ hg pull --config phases.publish=True -q -r 6 . # update phase of 6
  $ hg rebase -d 0 -b 6
  nothing to rebase
  [1]
  $ hg rebase -d 5 -b 6
  abort: can't rebase public changeset e1c4361dd923
  (see 'hg help phases' for details)
  [255]
  $ hg rebase -d 5 -r '1 + (6::)'
  abort: can't rebase public changeset e1c4361dd923
  (see 'hg help phases' for details)
  [255]

  $ hg rebase -d 5 -b 6 --keep
  rebasing 6:e1c4361dd923 "C"
  rebasing 7:c9659aac0000 "D" (tip)

Check rebasing mutable changeset
Source phase greater or equal to destination phase: new changeset get the phase of source:
  $ hg id -n
  5
  $ hg rebase -s9 -d0
  rebasing 9:2b23e52411f4 "D" (tip)
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/2b23e52411f4-f942decf-backup.hg (glob)
  $ hg id -n # check we updated back to parent
  5
  $ hg log --template "{phase}\n" -r 9
  draft
  $ hg rebase -s9 -d1
  rebasing 9:2cb10d0cfc6c "D" (tip)
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/2cb10d0cfc6c-ddb0f256-backup.hg (glob)
  $ hg log --template "{phase}\n" -r 9
  draft
  $ hg phase --force --secret 9
  $ hg rebase -s9 -d0
  rebasing 9:c5b12b67163a "D" (tip)
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/c5b12b67163a-4e372053-backup.hg (glob)
  $ hg log --template "{phase}\n" -r 9
  secret
  $ hg rebase -s9 -d1
  rebasing 9:2a0524f868ac "D" (tip)
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/2a0524f868ac-cefd8574-backup.hg (glob)
  $ hg log --template "{phase}\n" -r 9
  secret
Source phase lower than destination phase: new changeset get the phase of destination:
  $ hg rebase -s8 -d9
  rebasing 8:6d4f22462821 "C"
  saved backup bundle to $TESTTMP/a7/.hg/strip-backup/6d4f22462821-3441f70b-backup.hg (glob)
  $ hg log --template "{phase}\n" -r 'rev(9)'
  secret

  $ cd ..

Test for revset

We need a bit different graph
All destination are B

  $ hg init ah
  $ cd ah
  $ hg unbundle "$TESTDIR/bundles/rebase-revset.hg"
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 9 files (+2 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg tglog
  o  8: 'I'
  |
  o  7: 'H'
  |
  o  6: 'G'
  |
  | o  5: 'F'
  | |
  | o  4: 'E'
  |/
  o  3: 'D'
  |
  o  2: 'C'
  |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


Simple case with keep:

Source on have two descendant heads but ask for one

  $ hg clone -q -u . ah ah1
  $ cd ah1
  $ hg rebase -r '2::8' -d 1
  abort: can't remove original changesets with unrebased descendants
  (use --keep to keep original changesets)
  [255]
  $ hg rebase -r '2::8' -d 1 -k
  rebasing 2:c9e50f6cdc55 "C"
  rebasing 3:ffd453c31098 "D"
  rebasing 6:3d8a618087a7 "G"
  rebasing 7:72434a4e60b0 "H"
  rebasing 8:479ddb54a924 "I" (tip)
  $ hg tglog
  o  13: 'I'
  |
  o  12: 'H'
  |
  o  11: 'G'
  |
  o  10: 'D'
  |
  o  9: 'C'
  |
  | o  8: 'I'
  | |
  | o  7: 'H'
  | |
  | o  6: 'G'
  | |
  | | o  5: 'F'
  | | |
  | | o  4: 'E'
  | |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  o |  1: 'B'
  |/
  o  0: 'A'
  

  $ cd ..

Base on have one descendant heads we ask for but common ancestor have two

  $ hg clone -q -u . ah ah2
  $ cd ah2
  $ hg rebase -r '3::8' -d 1
  abort: can't remove original changesets with unrebased descendants
  (use --keep to keep original changesets)
  [255]
  $ hg rebase -r '3::8' -d 1 --keep
  rebasing 3:ffd453c31098 "D"
  rebasing 6:3d8a618087a7 "G"
  rebasing 7:72434a4e60b0 "H"
  rebasing 8:479ddb54a924 "I" (tip)
  $ hg tglog
  o  12: 'I'
  |
  o  11: 'H'
  |
  o  10: 'G'
  |
  o  9: 'D'
  |
  | o  8: 'I'
  | |
  | o  7: 'H'
  | |
  | o  6: 'G'
  | |
  | | o  5: 'F'
  | | |
  | | o  4: 'E'
  | |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  o |  1: 'B'
  |/
  o  0: 'A'
  

  $ cd ..

rebase subset

  $ hg clone -q -u . ah ah3
  $ cd ah3
  $ hg rebase -r '3::7' -d 1
  abort: can't remove original changesets with unrebased descendants
  (use --keep to keep original changesets)
  [255]
  $ hg rebase -r '3::7' -d 1 --keep
  rebasing 3:ffd453c31098 "D"
  rebasing 6:3d8a618087a7 "G"
  rebasing 7:72434a4e60b0 "H"
  $ hg tglog
  o  11: 'H'
  |
  o  10: 'G'
  |
  o  9: 'D'
  |
  | o  8: 'I'
  | |
  | o  7: 'H'
  | |
  | o  6: 'G'
  | |
  | | o  5: 'F'
  | | |
  | | o  4: 'E'
  | |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  o |  1: 'B'
  |/
  o  0: 'A'
  

  $ cd ..

rebase subset with multiple head

  $ hg clone -q -u . ah ah4
  $ cd ah4
  $ hg rebase -r '3::(7+5)' -d 1
  abort: can't remove original changesets with unrebased descendants
  (use --keep to keep original changesets)
  [255]
  $ hg rebase -r '3::(7+5)' -d 1 --keep
  rebasing 3:ffd453c31098 "D"
  rebasing 4:c01897464e7f "E"
  rebasing 5:41bfcc75ed73 "F"
  rebasing 6:3d8a618087a7 "G"
  rebasing 7:72434a4e60b0 "H"
  $ hg tglog
  o  13: 'H'
  |
  o  12: 'G'
  |
  | o  11: 'F'
  | |
  | o  10: 'E'
  |/
  o  9: 'D'
  |
  | o  8: 'I'
  | |
  | o  7: 'H'
  | |
  | o  6: 'G'
  | |
  | | o  5: 'F'
  | | |
  | | o  4: 'E'
  | |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  o |  1: 'B'
  |/
  o  0: 'A'
  

  $ cd ..

More advanced tests

rebase on ancestor with revset

  $ hg clone -q -u . ah ah5
  $ cd ah5
  $ hg rebase -r '6::' -d 2
  rebasing 6:3d8a618087a7 "G"
  rebasing 7:72434a4e60b0 "H"
  rebasing 8:479ddb54a924 "I" (tip)
  saved backup bundle to $TESTTMP/ah5/.hg/strip-backup/3d8a618087a7-b4f73f31-backup.hg (glob)
  $ hg tglog
  o  8: 'I'
  |
  o  7: 'H'
  |
  o  6: 'G'
  |
  | o  5: 'F'
  | |
  | o  4: 'E'
  | |
  | o  3: 'D'
  |/
  o  2: 'C'
  |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..


rebase with multiple root.
We rebase E and G on B
We would expect heads are I, F if it was supported

  $ hg clone -q -u . ah ah6
  $ cd ah6
  $ hg rebase -r '(4+6)::' -d 1
  rebasing 4:c01897464e7f "E"
  rebasing 5:41bfcc75ed73 "F"
  rebasing 6:3d8a618087a7 "G"
  rebasing 7:72434a4e60b0 "H"
  rebasing 8:479ddb54a924 "I" (tip)
  saved backup bundle to $TESTTMP/ah6/.hg/strip-backup/3d8a618087a7-aae93a24-backup.hg (glob)
  $ hg tglog
  o  8: 'I'
  |
  o  7: 'H'
  |
  o  6: 'G'
  |
  | o  5: 'F'
  | |
  | o  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  o |  1: 'B'
  |/
  o  0: 'A'
  
  $ cd ..

More complex rebase with multiple roots
each root have a different common ancestor with the destination and this is a detach

(setup)

  $ hg clone -q -u . a a8
  $ cd a8
  $ echo I > I
  $ hg add I
  $ hg commit -m I
  $ hg up 4
  1 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ echo I > J
  $ hg add J
  $ hg commit -m J
  created new head
  $ echo I > K
  $ hg add K
  $ hg commit -m K
  $ hg tglog
  @  10: 'K'
  |
  o  9: 'J'
  |
  | o  8: 'I'
  | |
  | o  7: 'H'
  | |
  +---o  6: 'G'
  | |/
  | o  5: 'F'
  | |
  o |  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
(actual test)

  $ hg rebase --dest 'desc(G)' --rev 'desc(K) + desc(I)'
  rebasing 8:e7ec4e813ba6 "I"
  rebasing 10:23a4ace37988 "K" (tip)
  saved backup bundle to $TESTTMP/a8/.hg/strip-backup/23a4ace37988-b06984b3-backup.hg (glob)
  $ hg log --rev 'children(desc(G))'
  changeset:   9:adb617877056
  parent:      6:eea13746799a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     I
  
  changeset:   10:882431a34a0e
  tag:         tip
  parent:      6:eea13746799a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     K
  
  $ hg tglog
  @  10: 'K'
  |
  | o  9: 'I'
  |/
  | o  8: 'J'
  | |
  | | o  7: 'H'
  | | |
  o---+  6: 'G'
  |/ /
  | o  5: 'F'
  | |
  o |  4: 'E'
  |/
  | o  3: 'D'
  | |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  

Test that rebase is not confused by $CWD disappearing during rebase (issue4121)

  $ cd ..
  $ hg init cwd-vanish
  $ cd cwd-vanish
  $ touch initial-file
  $ hg add initial-file
  $ hg commit -m 'initial commit'
  $ touch dest-file
  $ hg add dest-file
  $ hg commit -m 'dest commit'
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ touch other-file
  $ hg add other-file
  $ hg commit -m 'first source commit'
  created new head
  $ mkdir subdir
  $ cd subdir
  $ touch subfile
  $ hg add subfile
  $ hg commit -m 'second source with subdir'
#if rmcwd
  $ hg rebase -b . -d 1 --traceback
  rebasing 2:779a07b1b7a0 "first source commit"
  current directory was removed
  (consider changing to repo root: $TESTTMP/cwd-vanish)
  rebasing 3:a7d6f3a00bf3 "second source with subdir" (tip)
  saved backup bundle to $TESTTMP/cwd-vanish/.hg/strip-backup/779a07b1b7a0-853e0073-backup.hg (glob)
#else
  $ hg rebase -b . -d 1 --traceback
  rebasing 2:779a07b1b7a0 "first source commit"
  rebasing 3:a7d6f3a00bf3 "second source with subdir" (tip)
  saved backup bundle to $TESTTMP/cwd-vanish/.hg/strip-backup/779a07b1b7a0-853e0073-backup.hg (glob)
#endif

Get back to the root of cwd-vanish. Note that even though `cd ..`
works on most systems, it does not work on FreeBSD 10, so we use an
absolute path to get back to the repository.
  $ cd $TESTTMP

Test that rebase is done in topo order (issue5370)

  $ hg init order
  $ cd order
  $ touch a && hg add a && hg ci -m A
  $ touch b && hg add b && hg ci -m B
  $ touch c && hg add c && hg ci -m C
  $ hg up 1
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ touch d && hg add d && hg ci -m D
  created new head
  $ hg up 2
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ touch e && hg add e && hg ci -m E
  $ hg up 3
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ touch f && hg add f && hg ci -m F
  $ hg up 0
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ touch g && hg add g && hg ci -m G
  created new head

  $ hg tglog
  @  6: 'G'
  |
  | o  5: 'F'
  | |
  | | o  4: 'E'
  | | |
  | o |  3: 'D'
  | | |
  | | o  2: 'C'
  | |/
  | o  1: 'B'
  |/
  o  0: 'A'
  

  $ hg rebase -s 1 -d 6
  rebasing 1:76035bbd54bd "B"
  rebasing 2:d84f5cfaaf14 "C"
  rebasing 4:82ae8dc7a9b7 "E"
  rebasing 3:ab709c9f7171 "D"
  rebasing 5:412b391de760 "F"
  saved backup bundle to $TESTTMP/order/.hg/strip-backup/76035bbd54bd-e341bc99-backup.hg (glob)

  $ hg tglog
  o  6: 'F'
  |
  o  5: 'D'
  |
  | o  4: 'E'
  | |
  | o  3: 'C'
  |/
  o  2: 'B'
  |
  @  1: 'G'
  |
  o  0: 'A'
  

Test experimental revset
========================

  $ cd ../cwd-vanish

Make the repo a bit more interesting

  $ hg up 1
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo aaa > aaa
  $ hg add aaa
  $ hg commit -m aaa
  created new head
  $ hg log -G
  @  changeset:   4:5f7bc9025ed2
  |  tag:         tip
  |  parent:      1:58d79cc1cf43
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     aaa
  |
  | o  changeset:   3:1910d5ff34ea
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     second source with subdir
  | |
  | o  changeset:   2:82901330b6ef
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     first source commit
  |
  o  changeset:   1:58d79cc1cf43
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     dest commit
  |
  o  changeset:   0:e94b687f7da3
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     initial commit
  

Testing from lower head

  $ hg up 3
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg log -r '_destrebase()'
  changeset:   4:5f7bc9025ed2
  tag:         tip
  parent:      1:58d79cc1cf43
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     aaa
  

Testing from upper head

  $ hg log -r '_destrebase(4)'
  changeset:   3:1910d5ff34ea
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     second source with subdir
  
  $ hg up 4
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg log -r '_destrebase()'
  changeset:   3:1910d5ff34ea
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     second source with subdir