bug#63757: 29.0.91 order of package paths changed: random old versions of packages in load-path

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Philip Kaludercic <philipk@posteo.net>,  Eli Zaretskii <eliz@gnu.org>,
>   63757@debbugs.gnu.org
> Date: Sun, 04 Jun 2023 11:12:31 -0400
> 
> Sounds about right.  Except:
> 
> - We still need a `copy-sequence` to avoid `sort` side-effecting the
>   `package-alist` contents.
> - I'm not sure the change of `package-disabled-p` =>
>   `package-built-in-p` is right: it makes the code obey the comment, but
>   I don't think we want to prefer built-in packages.
> 
> With these two tweaks, I suspect it might actually really fix the bug in
> a way that should be safe enough for `emacs-29`.

I'd need to see the actual patch, but right now I'm inclined to leave
this problem unsolved in Emacs 29.  It only happens for people who
don't uninstall older versions of packages they install, and that's
not the workflow we support in Emacs 29.  The offending code was with
us since Aug 2022, so replacing it with something at the last moment
needs a very good reason.