bug#35420: Support git in ediff-patch-file

[Robert Pluim]

>>>>> On Thu, 25 Apr 2019 11:46:33 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Robert Pluim <rpluim@gmail.com> Cc: Juri Linkov
    >> <juri@linkov.net>, 35420@debbugs.gnu.org Date: Thu, 25 Apr 2019
    >> 09:53:16 +0200
    >> 
    >> You get i/, w/ and/or c/ when you run 'git diff' inside your
    >> working tree, depending on whether the changed file is in the
    >> 'i'ndex, 'w'orking tree, or 'c'ache (also known as the staging
    >> area). Things like 'git format-patch' and 'git show' use a/ and
    >> b/ by default.
    >> 
    >> And of course, since this is git, you can tell it to use other
    >> prefixes using '--src-prefix' and '--dst-prefix'.

    Eli> Thanks.  I guess we'd like to support these use cases as
    Eli> well, right?

Yes, that would be a good improvement.

    Eli> Also, what's the situation with hg?  Is it similar?

I donʼt use hg, but based on a quick test it uses a/ and b/

Robert