Subject: 28.0.50; undo comment-region error

From: Mattias Engdegård <[email-masked]>
Date: Wed, 11 Nov 2020 17:19:21 +0100

In *scratch*, write

abc def

Mark 'abc', run 'comment-region', then 'undo'.
This results in the error 

primitive-undo: Changes to be undone by function different from announced

with a backtrace if debug-on-error is set.