Subject: 28.0.50; undo comment-region error
From: Mattias Engdegård <[email-masked]>
To: [email-masked]
Date: Wed, 11 Nov 2020 17:19:21 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

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.