bug#4677: allow VC operations from dired

[Juri Linkov]

>   > > This patch allows VC operations to be run from dired.
>   > > State changing VC operations are not supported.
>   > > (only the various variations of log and diff)
>   >
>   > Thanks, it works right except in one case: when called outside of
>   > a repository controlled directory, it traverses all subdirectories
>   > trying to find a repository (I think traversing subdirectories
>   > makes no sense in this case) and later fails with:
>   >
>   >   Wrong type argument: stringp, nil
>
> Thanks.  Here's an updated patch.

Hmm, now it fails with "Directory not under VC" in all directories
even under version control since (vc-backend default-directory)
always returns nil.

-- 
Juri Linkov
http://www.jurta.org/emacs/