bug#60897: 29.0.60; vc-revert fails to revert buffer

[Juri Linkov]

>> >  (defun vc-resynch-buffer (file &optional keep noquery reset-vc-info)
>> >    "If FILE is currently visited, resynch its buffer."
>> > +  (unless (file-name-absolute-p file)
>> > +    (setq file (expand-file-name file (vc-root-dir))))
>> >    (if (string= buffer-file-name file)
>> >        (vc-resynch-window file keep noquery reset-vc-info)
>> >      (if (file-directory-p file)
>> 
>> Eli, is this ok for the emacs-29 branch?  I'm unsure because
>> vc-resynch-buffer is used in too many places, so this change
>> is not localized to vc-revert.
>
> You could use the expanded file name only for the purposes of the
> string= call, no?  Then the effect of this change would be very local
> and thus safer.

There is another string= call that fails inside vc-resynch-window
called from vc-resynch-buffer.