bug#19045: 25.0.50; [PATCH] vc-git-print-log use --follow

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Cc: 19045@debbugs.gnu.org
> Date: Sat, 10 Feb 2018 23:08:32 +0200
> 
> 0. emacs -Q
> 1. C-x d directory_under_Git_control
> 2. use customization or just (setq vc-git-print-log-follow t)
> 3. in Dired mark only one file
> 4. C-x v l   - works ok showing the log
> 5. mark a second file, so there are 2 marked files in Dired
> 6. C-x v l   - git fails with the following error message:
> 
>   “usage: git logs can only follow renames on one pathname at a time”
> 
> in git version 1.9.1

Thanks for the example, this works fine here with Git 2.10.0.

> So the fix was to check whether there is only one file given as an argument,
> and it is not a directory.

So I think we should disable multiple files only on old versions of
Git that don't support this.  Do we know which version started
supporting this?  And what about directories?

Thanks.