bug#66985: 29.1; Issue with `package.el` upgrading builtin (edge-case)

[Sylvain Bougerel]

I realised I wrote an inaccuracy in the bug report. This does not
change the issue or the outcome of the tests.

> `(seq "2.3")` is a version in the future, since `seq.el` is currently at 
> version 2.24.

This is incorrect for Emacs-29.1, which ships with `seq=2.23`.

> Emacs already has the latest version (2.24) and when 
> `package-install-upgrade-built-in` is not set.

The first half of this statement can be disregarded. However the
second half stands: since `package-install-upgrade-built-in` is not
set, the package should not be upgraded.

Regards,
Sylvain