tests/test-revlog-packentry.t

revset: add optimization for heads(commonancestors())

Previously, the only way to get these commits were (tested on
mozilla-central):

hg perfrevset 'heads(::a7cf55 and ::d8b15)'
! wall 4.988366 comb 4.960000 user 4.780000 sys 0.180000 (best of 3)

After this patch:

(python)
hg perfrevset 'heads(commonancestors(a7cf55 + d8b15))'
! wall 0.002155 comb 0.000000 user 0.000000 sys 0.000000 (best of 1107)

(C)
hg perfrevset 'heads(commonancestors(a7cf55 + d8b15))'
! wall 0.000568 comb 0.000000 user 0.000000 sys 0.000000 (best of 4646)

  $ hg init repo
  $ cd repo

  $ touch foo
  $ hg ci -Am 'add foo'
  adding foo

  $ hg up -C null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

this should be stored as a delta against rev 0

  $ echo foo bar baz > foo
  $ hg ci -Am 'add foo again'
  adding foo
  created new head

  $ hg debugindex foo
     rev linkrev nodeid       p1           p2
       0       0 b80de5d13875 000000000000 000000000000
       1       1 0376abec49b8 000000000000 000000000000

  $ cd ..