tests/test-merge-revert2.t

bdiff: adjust criteria for getting optimal longest match in the A side middle

We prefer matches closer to the middle to balance recursion, as introduced in
f1ca249696ed.

For ranges with uneven length, matches starting exactly in the middle should
have preference. That will be optimal for matches of length 1. We will thus
accept equality in the half check.

For ranges with even length, half was ceil'ed when calculated but we got the
preference for low matches from the 'less than half' check. To get the same
result as before when we also accept equality, floor it. Without that,
test-annotate.t would show some different (still correct but less optimal)
results.

This will change the heuristics. Tests shows a slightly different output - and
sometimes slightly smaller bundles.

The bundle size for 4.0 (hg bundle --base null -r 4.0 x.hg) happens to go from
22804885 to 22803824 bytes - an 0.005% reduction.

  $ hg init

  $ echo "added file1" > file1
  $ echo "another line of text" >> file1
  $ echo "added file2" > file2
  $ hg add file1 file2
  $ hg commit -m "added file1 and file2"

  $ echo "changed file1" >> file1
  $ hg commit -m "changed file1"

  $ hg -q log
  1:dfab7f3c2efb
  0:c3fa057dd86f
  $ hg id
  dfab7f3c2efb tip

  $ hg update -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id
  c3fa057dd86f

  $ echo "changed file1" >> file1
  $ hg id
  c3fa057dd86f+

  $ hg revert --no-backup --all
  reverting file1
  $ hg diff
  $ hg status
  $ hg id
  c3fa057dd86f

  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg diff
  $ hg status
  $ hg id
  dfab7f3c2efb tip

  $ hg update -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "changed file1 different" >> file1

  $ hg update
  merging file1
  warning: conflicts while merging file1! (edit, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges
  [1]

  $ hg diff --nodates
  diff -r dfab7f3c2efb file1
  --- a/file1
  +++ b/file1
  @@ -1,3 +1,7 @@
   added file1
   another line of text
  +<<<<<<< working copy: c3fa057dd86f  - test: added file1 and file2
  +changed file1 different
  +=======
   changed file1
  +>>>>>>> destination:  dfab7f3c2efb - test: changed file1

  $ hg status
  M file1
  ? file1.orig
  $ hg id
  dfab7f3c2efb+ tip

  $ hg revert --no-backup --all
  reverting file1
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  dfab7f3c2efb tip

  $ hg revert -r tip --no-backup --all
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  dfab7f3c2efb tip

  $ hg update -C
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg diff
  $ hg status
  ? file1.orig
  $ hg id
  dfab7f3c2efb tip