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

[Dmitry Gutov <dmitry@gutov.dev>]

Version: 30.1

On 15/08/2023 21:52, Bob Rogers wrote:
>     1.  On a system with a version of Git older than 2.7.0, navigate to a
> git-controlled directory and invoke "emacs -Q".
> 
>     2.  With this as the default directory, invoke vc-dir.  This fails
> with the error "vc-do-command: Failed (status 129): git --no-pager
> remote get-url origin ."
> 
>     This is because the "get-url" subcommand of "git remote", used by
> vc-git-repository-url, was added in 2.7.0 [1].  The attached patch
> against master rev 1db7e8eba961e88181879213dd5374ad9e87ac76 uses "git
> config" in a way that works in both old and new systems (tested with git
> 2.1.2 and git 2.35.3).

Thanks! Pushed to master.

>     Of course, supporting 7+-year-old versions of git is probably not a
> high priority, so I won't be too disappointed if this fix is rejected.
> On the other hand, it's a small change, and having vc-dir fail on any
> system, especially when using Git, puts a big damper on being able to
> use Emacs to hack on things in older systems, so I think it's worth
> having.

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.

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.