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

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

> But in this case, if a regular package is upgraded, and a VC package
> weren't (even though the user might have written some patch they are
> relying on), it would be suddenly switch when starting up Emacs at some
> point.

Yup.  AFAIK both behaviors (staying with the VC package, and
switching to the non-VC package) can be "incorrect", depending on
the circumstances.  So I don't see this as "a bug".

Note also that in the session where we perform the install of the
upgraded package, the upgraded package will take precedence over the VC
package, so it's mildly more consistent to do the same at startup.

If the user wants to keep using the older VC package, there's always to
option to use `package-pinned-packages` or to remove the non-VC package.

If we want to do better, rather than forcing VC packages to the top we
should detect when the ordering between VC and non-VC packages changes
and emit a warning or prompt the user.


        Stefan