comparison tests/test-bdiff.py.out @ 30433:96f2f50d923f

bdiff: give slight preference to removing trailing lines

[This change could be folded into the previous changeset to minimize the repo
churn ...]

Similar to the previous change, introduce an exception to the general
preference for matches in the middle of bdiff ranges: If the best match on the
B side starts at the beginning of the bdiff range, don't aim for the
middle-most A side match but for the earliest.

New (later) matches on the A side will only be considered better if the
corresponding match on the B side *not* is at the beginning of the range.
Thus, if the best (middle-most) match on the B side turns out to be at the
beginning of the range, the earliest match on the A side will be used.

The bundle size for 4.0 (hg bundle --base null -r 4.0 x.hg) happens to go from
22807275 to 22808120 bytes - a 0.004% increase.

30432:3633403888ae

showdiff(
  'a\n',
  'a\na\na\na\na\n'):
 'a\n'
 2 2 '' -> 'a\na\na\na\n'
Diff 3 to 1 lines - preference for balanced recursion:
showdiff(
  'a\na\na\n',
  'a\n'):
 0 2 'a\n' -> ''
 'a\n'
 4 6 'a\n' -> ''
Diff 5 to 1 lines - preference for balanced recursion:
showdiff(
  'a\na\na\na\na\n',
  'a\n'):
 0 4 'a\na\n' -> ''
 'a\n'
 6 10 'a\na\n' -> ''

30433:96f2f50d923f

showdiff(
  'a\n',
  'a\na\na\na\na\n'):
 'a\n'
 2 2 '' -> 'a\na\na\na\n'
Diff 3 to 1 lines - preference for removing trailing lines:
showdiff(
  'a\na\na\n',
  'a\n'):
 'a\n'
 2 6 'a\na\n' -> ''
Diff 5 to 1 lines - preference for removing trailing lines:
showdiff(
  'a\na\na\na\na\n',
  'a\n'):
 'a\n'
 2 10 'a\na\na\na\n' -> ''