bug#60467: 30.0.50; primitive-undo: Changes to be undone by function different from announced

[sbaugh]

Incidentally, this bug has an easy reproduction in emacs -Q on Emacs 29
and before:

(with-temp-buffer
  (insert "foo")
  (setq-local buffer-undo-list nil
              comment-start    ";")
  (comment-line 1))

which produces the "combine-change-calls: buffer-undo-list broken"
warning.  This is easy to trigger in practice: simply open a file
already containing text, and comment a line as your first action.

Anyway, this was also fixed by Stefan's change 977630b5285809a57e50,
* lisp/subr.el (combine-change-calls-1): Fix bug#60467

(I send this email just because I spent some time tracking this down
only to find it was already fixed.  Maybe my smallish reproducer will
somehow be helpful to someone...)