[PATCH STABLE] status: don't crash if a lookup file disappears

[Yuya Nishihara]

On Fri, 2 Jun 2017 22:28:07 -0700, Siddharth Agarwal wrote:
> # HG changeset patch
> # User Siddharth Agarwal <sid0 at fb.com>
> # Date 1496467672 25200
> #      Fri Jun 02 22:27:52 2017 -0700
> # Branch stable
> # Node ID d39f934da0c80a568486cd8645eb6bbe513f1f03
> # Parent  62e42e2897502bcbaa3a57d3301c789309596391
> status: don't crash if a lookup file disappears

Looks good to me. A few nits.

> diff --git a/mercurial/context.py b/mercurial/context.py
> --- a/mercurial/context.py
> +++ b/mercurial/context.py
> @@ -1613,18 +1613,30 @@ class workingctx(committablectx):
>      def _checklookup(self, files):
>          # check for any possibly clean files
>          if not files:
> -            return [], []
> +            return [], [], []
>  
>          modified = []
> +        deleted = []
>          fixup = []
>          pctx = self._parents[0]
>          # do a full compare of any files that might have changed
>          for f in sorted(files):
> -            if (f not in pctx or self.flags(f) != pctx.flags(f)
> -                or pctx[f].cmp(self[f])):
> -                modified.append(f)
> -            else:
> -                fixup.append(f)
> +            try:
> +                # This will return True for a file that got replaced by a
> +                # directory in the interim, but fixing that is pretty hard.
> +                if (f not in pctx or self.flags(f) != pctx.flags(f)
> +                    or pctx[f].cmp(self[f])):

If cmp() falls back to fctx.data() path, maybe IOError could be raised.

> +                    modified.append(f)
> +                else:
> +                    fixup.append(f)
> +            except OSError:

Can we check errno strictly? Perhaps ENOENT and EISDIR should be caught.