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

[Eli Zaretskii]

> From: Евгений Бойков <artscan@list.ru>
> Date: Sun, 4 Jun 2023 15:37:31 +1000
> Cc: Philip Kaludercic <philipk@posteo.net>, Eli Zaretskii <eliz@gnu.org>, 
> 63757@debbugs.gnu.org
> 
> Excuse me for extra messages, I've already found a bug in the previous patch.
> I need a review, especially with in-place operations.
> 
> move "Prefer VC packages" to `package-process-define-package`
> drop `package-disabled-p` and "Prefer builtin packages" comment

Thanks, but I'm not really comfortable with such non-trivial changes
in package.el at this late stage of the pretest.

Is this problem new in Emacs 29, or did it exist in Emacs 28 as well?
If it is new, which change(s) caused the incorrect ordering of
versions in Emacs 29?