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

[Dmitry Gutov <dmitry@gutov.dev>]

On 13/04/2023 19:40, Olivier Certner wrote:
> Hi,
> 
> Thanks for looking at this.
> 
>> - 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.
> 
> It's not that files are not listed, they are so always. As said, the problem
> is their name. For example, if I remove an INSTALL file in a repository,
> `INSTALL' is the name listed in a VC dir buffer, *quotes included*. Then, no
> VC operation can work because there is indeed no file by this name (with
> quotes, both in the filesystem or known by CVS).

So the actual file name is not the problem -- the problem happens with 
removed files?

Okay, I can see that now: when the file is removed, it's displayed 
(incorrectly) with quotes around its name. Patches 2 and 3 do fix the 
remove - vc-dir - vc-revert scenario.

Eli, do we want these fixes in emacs-29? These are again not 
regressions, but I'm guessing users of CVS are foremost to benefit from 
adding this to the upcoming release.

>> - Could you give an example of the repository CVS root which is
>> recognized by the current code incorrectly?
> 
> Just run (vc-cvs-parse-root "/your/local/path/to/some/CVS/repo") and you'll
> see...
> 
> I've found more occurences of problems with this function, so my initial fix
> is not enough. I went ahead and rewrote it completely. So please forget about
> the original first patch, and consider it replaced by the attached one. The
> commit message there explains how you can reproduce the bugs I found and shows
> that the new version fixes them.

Thank you. What was the effect of wrong local/nonlocal recognition, 
though? Some misbehavior related to cvs-stay-local?

Regarding the new patch, it's great to see the list of examples, but 
could you instead move it to a test or several inside 
test/lisp/vc/vc-cvs-tests.el? This file does not exist yet, but you can 
use vc-git-test.el as an example, in the same directory.