tests/test-rebase-emptycommit.t

rebase: move bookmark to destination for commits becoming empty (issue5627)

When rebasing a changeset X and that changeset becomes empty, we should move
the bookmark on X to rebase destination.

This is a regression caused by the scmutil.cleanupnodes refactoring for
rebase.

The `adjustdest` function calculates the destination of bookmark movement.
It was back-ported from https://phab.mercurial-scm.org/D21. It might be
slightly more powerful than the minimal requirement to solve this issue.
For example, it's impossible for a merge changeset to become empty while any
of its ancestors does not become empty, but the code could handle that case.
Since the code is reasonably short and clean, and helps the upcoming D21
series, I'd like to check-in `adjustdest` now.

Thanks Martin von Zweigbergk for spotting corner cases (-k and descendant
with bookmarks) in this area!

  $ cat >> $HGRCPATH<<EOF
  > [extensions]
  > rebase=
  > drawdag=$TESTDIR/drawdag.py
  > EOF

  $ hg init non-merge
  $ cd non-merge
  $ hg debugdrawdag<<'EOS'
  >   F
  >   |
  >   E
  >   |
  >   D
  >   |
  > B C
  > |/
  > A
  > EOS

  $ for i in C D E F; do
  >   hg bookmark -r $i -i BOOK-$i
  > done

  $ hg debugdrawdag<<'EOS'
  > E
  > |
  > D
  > |
  > B
  > EOS

  $ hg log -G -T '{rev} {desc} {bookmarks}'
  o  7 E
  |
  o  6 D
  |
  | o  5 F BOOK-F
  | |
  | o  4 E BOOK-E
  | |
  | o  3 D BOOK-D
  | |
  | o  2 C BOOK-C
  | |
  o |  1 B
  |/
  o  0 A
  
With --keep, bookmark should not move

  $ hg rebase -r 3+4 -d E --keep
  rebasing 3:e7b3f00ed42e "D" (BOOK-D)
  note: rebase of 3:e7b3f00ed42e created no changes to commit
  rebasing 4:69a34c08022a "E" (BOOK-E)
  note: rebase of 4:69a34c08022a created no changes to commit
  $ hg log -G -T '{rev} {desc} {bookmarks}'
  o  7 E
  |
  o  6 D
  |
  | o  5 F BOOK-F
  | |
  | o  4 E BOOK-E
  | |
  | o  3 D BOOK-D
  | |
  | o  2 C BOOK-C
  | |
  o |  1 B
  |/
  o  0 A
  
Bookmark is usually an indication of a head. For changes that are introduced by
an ancestor of bookmark B, after moving B to B-NEW, the changes are ideally
still introduced by an ancestor of changeset on B-NEW. In the below case,
"BOOK-D", and "BOOK-E" include changes introduced by "C".

  $ hg rebase -s 2 -d E
  rebasing 2:dc0947a82db8 "C" (C BOOK-C)
  rebasing 3:e7b3f00ed42e "D" (BOOK-D)
  note: rebase of 3:e7b3f00ed42e created no changes to commit
  rebasing 4:69a34c08022a "E" (BOOK-E)
  note: rebase of 4:69a34c08022a created no changes to commit
  rebasing 5:6b2aeab91270 "F" (F BOOK-F)
  saved backup bundle to $TESTTMP/non-merge/.hg/strip-backup/dc0947a82db8-52bb4973-rebase.hg (glob)
  $ hg log -G -T '{rev} {desc} {bookmarks}'
  o  5 F BOOK-F
  |
  o  4 C BOOK-C BOOK-D BOOK-E
  |
  o  3 E
  |
  o  2 D
  |
  o  1 B
  |
  o  0 A
  
Merge and its ancestors all become empty

  $ hg init $TESTTMP/merge1
  $ cd $TESTTMP/merge1

  $ hg debugdrawdag<<'EOS'
  >     E
  >    /|
  > B C D
  >  \|/
  >   A
  > EOS

  $ for i in C D E; do
  >   hg bookmark -r $i -i BOOK-$i
  > done

  $ hg debugdrawdag<<'EOS'
  > H
  > |
  > D
  > |
  > C
  > |
  > B
  > EOS

  $ hg rebase -r '(A::)-(B::)-A' -d H
  rebasing 2:dc0947a82db8 "C" (BOOK-C)
  note: rebase of 2:dc0947a82db8 created no changes to commit
  rebasing 3:b18e25de2cf5 "D" (BOOK-D)
  note: rebase of 3:b18e25de2cf5 created no changes to commit
  rebasing 4:86a1f6686812 "E" (E BOOK-E)
  note: rebase of 4:86a1f6686812 created no changes to commit
  saved backup bundle to $TESTTMP/merge1/.hg/strip-backup/b18e25de2cf5-1fd0a4ba-rebase.hg (glob)

  $ hg log -G -T '{rev} {desc} {bookmarks}'
  o  4 H BOOK-C BOOK-D BOOK-E
  |
  o  3 D
  |
  o  2 C
  |
  o  1 B
  |
  o  0 A
  
Part of ancestors of a merge become empty

  $ hg init $TESTTMP/merge2
  $ cd $TESTTMP/merge2

  $ hg debugdrawdag<<'EOS'
  >     G
  >    /|
  >   E F
  >   | |
  > B C D
  >  \|/
  >   A
  > EOS

  $ for i in C D E F G; do
  >   hg bookmark -r $i -i BOOK-$i
  > done

  $ hg debugdrawdag<<'EOS'
  > H
  > |
  > F
  > |
  > C
  > |
  > B
  > EOS

  $ hg rebase -r '(A::)-(B::)-A' -d H
  rebasing 2:dc0947a82db8 "C" (BOOK-C)
  note: rebase of 2:dc0947a82db8 created no changes to commit
  rebasing 3:b18e25de2cf5 "D" (D BOOK-D)
  rebasing 4:03ca77807e91 "E" (E BOOK-E)
  rebasing 5:ad6717a6a58e "F" (BOOK-F)
  note: rebase of 5:ad6717a6a58e created no changes to commit
  rebasing 6:c58e8bdac1f4 "G" (G BOOK-G)
  saved backup bundle to $TESTTMP/merge2/.hg/strip-backup/b18e25de2cf5-2d487005-rebase.hg (glob)

  $ hg log -G -T '{rev} {desc} {bookmarks}'
  o    7 G BOOK-G
  |\
  | o  6 E BOOK-E
  | |
  o |  5 D BOOK-D BOOK-F
  |/
  o  4 H BOOK-C
  |
  o  3 F
  |
  o  2 C
  |
  o  1 B
  |
  o  0 A