bug#65315: 30.0.50; vc-dir fails with Git < 2.7.0

[Bob Rogers]

   From: Dmitry Gutov <dmitry@gutov.dev>
   Date: Wed, 16 Aug 2023 04:33:04 +0300

   . . .

   I'm not a fan of spending too much time on older versions myself, but 
   the patch is indeed small, and we're still making allowances for 
   versions older than that still.

Great; thank you.

   Speaking of older systems, though, I would hope they have similarly
   old repositories with suitably old Emacs versions (or, if you build
   from source, there is a respective tag in the repo).  We do have to
   drop compatibilities when stuff is old enough.

Understood.  I have been building emacs from master in order to have all
my latest customizations on this system; really what I suppose I ought
to do is create a branch (or two) of my customizations and revert the
relevant updates.  Fortunately, I no longer need to hack on this system
very often.

                                        -- Bob