D1057: use arbitraryfilectx for backups

[phillco (Phil Cohen)]

phillco added inline comments.

INLINE COMMENTS

> durin42 wrote in filemerge.py:604
> Well that's a bummer. Could we move context.*filectx* into mercurial.filecontext and then avoid the need for this function-level import?

I don't think so, because the filectx classes reference the ctx classes in various places.

REPOSITORY
  rHG Mercurial

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

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