bug#67568: Emacs master: Bug in byte compiler when there's an unused parameter.

[Stefan Monnier]

>> I think the patch below should fix it.
> It certainly will in the test case, yes.
> I think I understand the function better now, thanks.
> Are you going to commit your patch, or should I?  :-)

I'm wondering whether it should go to `emacs-29` or to `master`.
I'm leaning toward `emacs-29` because it's rather embarrassing (and
perplexing for the user) and the patch is simple.
Eli?  Stefan?


        Stefan