bug#64821: 30.0.50; write-region errs when overwriting an already open file

[Eli Zaretskii]

> From: Mattias Engdegård <mattias.engdegard@gmail.com>
> Date: Thu, 27 Jul 2023 21:49:12 +0200
> Cc: yantar92@gmail.com,
>  64821@debbugs.gnu.org
> 
> 27 juli 2023 kl. 21.02 skrev Eli Zaretskii <eliz@gnu.org>:
> 
> > Thanks, but I think we should make userlock.el robust in the face of
> > such applications.  How about the patch below instead?
> 
> That prevent the error but the test then fails since the modtime isn't 
> actually changed.

That's okay: it just means we need to install your suggested patch to
the test as well.  Here, done.  Can you test and see that the test now
succeeds for you?