bug#58525: 28.1: `vc-dir' (key sequence: C-x v d) fails when used with a CVS repository

[Dmitry Gutov]

On 17.10.2022 09:06, Eli Zaretskii wrote:
> AFAIK, the VC's support for CVS is based on detecting the CVS
> subdirectory of a directory where you invoke vc-dir.  If that
> subdirectory is not found, VC will assume the backend is not CVS.  In
> which case your assumptions seem to be mistaken.
>
> But I will let VC expert to chime in here, because I may be wrong or
> confused.

Here's the basic logic:

(defun vc-cvs-registered (f)
  "Return non-nil if file F is registered with CVS."
  (when (file-readable-p (expand-file-name
                          "CVS/Entries" (file-name-directory f)))
    ...