bug#53636: 29.0.50; face-remapping broken on master

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Sun, 30 Jan 2022 18:41:36 +0100
> Cc: 53636@debbugs.gnu.org
> 
> Tassilo Horn <tsdh@gnu.org> writes:
> 
> > I've also tried with master and --without-pgtk.  There it seems to be
> > broken, too, i.e., after evaling the code above, C-g or errors won't
> > flash the mode-line (but I can't say anything about the "suddenly the
> > error face sticks" issue).
> 
> I can confirm that I'm also seeing the bug on master, but not on
> emacs-28 (with just ./configure on Debian/bookworm).

If the problem is with face remapping, can we please have a reproducer
that is simpler to debug?  Like one that doesn't need any timers and
flashing text?

TIA