Re: [PATCH v2] diff: handle --no-abbrev outside of repository

> On Mon, Dec 05, 2016 at 01:01:16AM -0500, Jeff King wrote:
> 
> >   Note that setting abbrev to "0" outside of a repository was broken
> >   recently by 4f03666ac (diff: handle sha1 abbreviations outside of
> >   repository, 2016-10-20). It adds a special out-of-repo code path for
> >   handling abbreviations which behaves differently than find_unique_abbrev()
> >   by truly giving a zero-length sha1, rather than taking "0" to mean "do
> >   not abbreviate".
> > 
> >   That bug was not triggerable until now, because there was no way to
> >   set the value to zero (using --abbrev=0 silently bumps it to the
> >   MINIMUM_ABBREV).
> 
> Actually, I take this last paragraph back. You _can_ trigger the bug
> with just:
> 
>   echo one >foo
>   echo two >bar
>   git diff --no-index --raw foo bar
> 
> which prints only "..." for each entry.
> 
> I didn't notice it before because without "--raw", we show the patch
> format. That uses the --full-index option, and does not respect --abbrev
> at all (which seems kind of bizarre, but has been that way forever).
> 
> So I think there _is_ a regression in v2.11, and the second half of your
> change fixes it.