On Sat, 6 Feb 2021 at 11:27, Reuben Thomas <rrt@sc3d.org> wrote:
I just looked at the history of provided-mode-derived-p, and it seems that a fix had already been made for this problem. See commit 48ff4c0b2f7. (I am using emacs 26.3, which does not have this fix.)
Ah, sorry, the earlier fix is for when one of MODES is an alias, not for when MODE is an alias!