D7465: filemerge: fix a missing attribute usage

[dlax (Denis Laxalde)]

dlax added inline comments.

INLINE COMMENTS

> filemerge.py:122
>              fctx.isabsent()
> -            and fctx.ctx() == self.ctx()
> +            and fctx.ctx() == self._ctx
>              and fctx.path() == self.path()

What about `fctx`? It could also lack the `ctx()` method if an instance of `absentfilectx`.
I wonder if the intent was not `fctx.changectx() == self.changectx()`.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D7465/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D7465

To: mharbison72, #hg-reviewers
Cc: dlax, mercurial-devel