Subject: bug#33341: 27.0.50; Undo log merging and change groups

From: Michael Heerdegen <[email-masked]>
Date: Thu, 26 Nov 2020 21:26:03 +0100

Michael Heerdegen <[email-masked]> writes:

#+begin_src emacs-lisp
(defun my-test-change-groups ()
  (interactive)
  (insert "0\n")
  (let ((g (prepare-change-group)))
    (activate-change-group g)
    (insert "b\n")
    (insert "c\n")
    (cancel-change-group g)))
#+end_src

Adding an explicit `undo-boundary' call before preparing the change
group fixes the problem for me.  Should `prepare-change-group' do
something like that implicitly?

Michael.