D2577: mdiff: prefer xdiff for diff calculation

[durin42 (Augie Fackler)]

durin42 added inline comments.

INLINE COMMENTS

> mdiff.py:34
>  
> +try:
> +    from .cext import xdiff

Rather than this, let's try to get the xdiffblocks function (and if it's not there set it to none), and then we could rework the below code to use xdiffblocks instead of blocks if experimental.xdiff is set to true - that'll make it easier to do some testing of both codepaths.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D2577

To: ryanmce, #hg-reviewers
Cc: durin42, mercurial-devel