Re: emacs-28 bc63651588: Make all vc-*-responsible-p functions return a string

[Stefan Monnier]

>     Make all vc-*-responsible-p functions return a string
>     
>     * lisp/vc/vc-sccs.el (vc-sccs-responsible-p):
>     * lisp/vc/vc-rcs.el (vc-rcs-responsible-p):
>     * lisp/vc/vc-dav.el (vc-dav-responsible-p):
>     * lisp/vc/vc-cvs.el (vc-cvs-responsible-p): Return a file name
>     instead of t when we get a match (which is what
>     vc-backend-for-registration expects) (bug#51800).
>     
>     This fixes the regression reported in bug#54935.

Could you change the docstrings accordingly (they all say just
"non-nil") and more importantly the doc of `responsible-p` in the header
of `vc.el` which still says:

;; - responsible-p (file)
;;
;;   Return non-nil if this backend considers itself "responsible" for
;;   FILE, which can also be a directory.  This function is used to find
;;   out what backend to use for registration of new files and for things
;;   like change log generation.  The default implementation always
;;   returns nil.


        Stefan