tests/test-double-merge.t

scmutil: make cleanupnodes delete divergent bookmarks

cleanupnodes takes care of bookmark movement, and bookmark movement could
cause bookmark divergent resolution as a side effect. This patch adds such
bookmark divergent resolution logic so future rebase migration will be
easier.

The revset is carefully written to be equivalent to what rebase does today.
Although I think it might make sense to remove divergent bookmarks more
aggressively, for example:

    F   book@1
    |
    E   book@2
    |
    | D book
    | |
    | C
    |/
    B   book@3
    |
    A

When rebase -s C -d E, "book@1" will be removed, "book@3" will be kept,
and the end result is:

    D   book
    |
    C
    |
    F
    |
    E   book@2 (?)
    |
    B   book@3
    |
    A

The question is should we keep book@2? The current logic keeps it. If we
choose not to (makes some sense to me), the "deleterevs" revset could be
simplified to "newnode % oldnode".

For now, I just make it compatible with the existing behavior. If we want to
make the "deleterevs" revset simpler, we can always do it in the future.

  $ hg init repo
  $ cd repo

  $ echo line 1 > foo
  $ hg ci -qAm 'add foo'

copy foo to bar and change both files
  $ hg cp foo bar
  $ echo line 2-1 >> foo
  $ echo line 2-2 >> bar
  $ hg ci -m 'cp foo bar; change both'

in another branch, change foo in a way that doesn't conflict with
the other changes
  $ hg up -qC 0
  $ echo line 0 > foo
  $ hg cat foo >> foo
  $ hg ci -m 'change foo'
  created new head

we get conflicts that shouldn't be there
  $ hg merge -P
  changeset:   1:484bf6903104
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     cp foo bar; change both
  
  $ hg merge --debug
    searching for copies back to rev 1
    unmatched files in other:
     bar
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'foo' -> dst: 'bar' *
    checking for directory renames
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: e6dc8efe11cc, local: 6a0df1dad128+, remote: 484bf6903104
   preserving foo for resolve of bar
   preserving foo for resolve of foo
  starting 4 threads for background file closing (?)
   bar: remote copied from foo -> m (premerge)
  picked tool ':merge' for bar (binary False symlink False changedelete False)
  merging foo and bar to bar
  my bar@6a0df1dad128+ other bar@484bf6903104 ancestor foo@e6dc8efe11cc
   premerge successful
   foo: versions differ -> m (premerge)
  picked tool ':merge' for foo (binary False symlink False changedelete False)
  merging foo
  my foo@6a0df1dad128+ other foo@484bf6903104 ancestor foo@e6dc8efe11cc
   premerge successful
  0 files updated, 2 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

contents of foo
  $ cat foo
  line 0
  line 1
  line 2-1

contents of bar
  $ cat bar
  line 0
  line 1
  line 2-2

  $ cd ..