bug#43464: 28.0.50; vc: Error calling vc-revert for repo root

[Andrii Kolomoiets]

Dmitry Gutov <dgutov@yandex.ru> writes:

> Where is that vc-backend called from, in our scenario?

It's called from 'vc-call'.  The 'vc-revert-file' used it twice
to call the 'make-version-backups-p' and the 'revert' backend functions.

> Could we make do with changing that code to use vc-responsible-backend
> instead of vc-backend instead? If it's not a function called
> frequently.

I went a little different way and made the 'vc-backend' return correct
backend for directories.  In case you missed it somehow here is the link
to the message:

https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-09/msg02508.html