tests/test-copy-move-merge.t

manifestmerge: fix order in which manifests are fetched

If the manifest of an earlier revision on the same delta chain is read before
that of a later revision, the revlog remembers that we parsed the earlier
revision and continues applying deltas from there onwards. If manifests are
parsed the other way round, we have to start over from the fulltext.

For a fresh clone of mozilla-central, updating from 29dd80c95b7d to its parent
aab96936a177 requires approximately 400 fewer zlib.decompress calls, which
results in a speedup from 1.10 seconds to 1.05.

  $ hg init t
  $ cd t

  $ echo 1 > a
  $ hg ci -qAm "first"

  $ hg cp a b
  $ hg mv a c
  $ echo 2 >> b
  $ echo 2 >> c

  $ hg ci -qAm "second"

  $ hg co -C 0
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved

  $ echo 0 > a
  $ echo 1 >> a

  $ hg ci -qAm "other"

  $ hg merge --debug
    searching for copies back to rev 1
    unmatched files in other:
     b
     c
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'a' -> dst: 'b' *
     src: 'a' -> dst: 'c' *
    checking for directory renames
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: b8bf91eeebbc, local: add3f11052fa+, remote: 17c05bb7fcb6
   a: remote moved to b -> m
    preserving a for resolve of b
   a: remote moved to c -> m
    preserving a for resolve of c
  removing a
  updating: a 1/2 files (50.00%)
  picked tool 'internal:merge' for b (binary False symlink False)
  merging a and b to b
  my b@add3f11052fa+ other b@17c05bb7fcb6 ancestor a@b8bf91eeebbc
   premerge successful
  updating: a 2/2 files (100.00%)
  picked tool 'internal:merge' for c (binary False symlink False)
  merging a and c to c
  my c@add3f11052fa+ other c@17c05bb7fcb6 ancestor a@b8bf91eeebbc
   premerge successful
  0 files updated, 2 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

file b
  $ cat b
  0
  1
  2

file c
  $ cat c
  0
  1
  2

  $ cd ..