D1057: filemerge: use arbitraryfilectx for backups

[phillco (Phil Cohen)]

phillco marked 4 inline comments as done.
phillco added inline comments.

INLINE COMMENTS

> phillco wrote in filemerge.py:604
> Sure, will do. I think most likely by breaking the context -> fileset dependency.

@durin42 done

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1057

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