tests/test-merge5.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
  $ echo This is file a1 > a
  $ echo This is file b1 > b
  $ hg add a b
  $ hg commit -m "commit #0"
  $ echo This is file b22 > b
  $ hg commit -m "comment #1"
  $ hg update 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm b
  $ hg commit -A -m "comment #2"
  removing b
  created new head
  $ hg update 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg update
  abort: crosses branches (merge branches or update --check to force update)
  [255]
  $ rm b
  $ hg update -c
  abort: uncommitted local changes
  [255]
  $ hg revert b
  $ hg update -c
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mv a c

In theory, we shouldn't need the "-y" below, but it prevents this test
from hanging when "hg update" erroneously prompts the user for "keep
or delete".

Should abort:

  $ hg update -y 1
  abort: crosses branches (merge branches or use --clean to discard changes)
  [255]
  $ mv c a

Should succeed:

  $ hg update -y 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved