bug#62693: 28.2; VC: CVS: Fix lost file reporting and enable reverting it

[Dmitry Gutov]

Hi! Thanks for the report.

On 06/04/2023 12:51, Olivier Certner wrote:

> When using CVS 1.12.3+, VC dir doesn't list correctly some missing file, including quotes 
> produced by CVS in the file name, then preventing to operate on it. The fix works on all 
> "recent" versions of CVS (1.11 and 1.12).
>
> Once this is fixed, it's still not possible to revert such a file yet since 
> `vc-default-revert', called by `vc-cvs-revert', tries to backup the 
> non-existing file (`copy-file' just fails).
>
> While here, fixed `vc-cvs-parse-root', which is not correctly reporting whether 
> some repository is local.
>
> All three patches can be applied to 'master' directly (e579c9cc33d).

Regarding patches 1 and 3:

- Could you explain what kind of files are not listed and when? I'm 
guessing this has to do with the file name? I've tried to reproduce the 
problem with a file name that contained a space, and couldn't see it.

- Could you give an example of the repository CVS root which is 
recognized by the current code incorrectly?