bug#65049: Minor update to the repro steps

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: Maxim Kim <habamax@gmail.com>,  Dmitry Gutov <dmitry@gutov.dev>,
>   65049@debbugs.gnu.org
> Date: Wed, 23 Aug 2023 20:42:38 +0300
> 
> > +    (if (and (memq system-type '(windows-nt ms-dos))
> > +             (not (eq (vc-deduce-backend) 'Git)))
> 
> Possible optimization: the backend is already in (car vc-fileset).

Thanks, will use that.