D2686: xdiff: add a preprocessing step that trims files

[quark (Jun Wu)]

quark added a comment.


  The patch sent to the git list was completely different from this one, because git has another layer `xdiff-interface.c` and trimming happens there. git also has some more complexity like context line handling, which is the hard part.
  
  Since the context lines logic was removed and Mercurial does context line in a higher layer, the git upstream's concerns about context lines are invalid here.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2686

To: quark, #hg-reviewers
Cc: indygreg, mercurial-devel