bug#60467: New problem introduced

[Frédéric Giquel]

Hi all,

I'm reopening this bug because the fix has introduced a new problem.

This can be highlighted with the following procedure (verified with
Emacs 29.0.92) :
1. Open a file: emacs -Q <file>
2. Move point to a line you can comment
3. M-x comment-line
4. M-x undo
5. Check buffer modification status in modeline or use (buffer-
modified-p)

Without the patched version of combine-change-calls-1, the buffer
status is "not modified since last save". Same result if you use
another command, for example kill-line,  at step 2.
With new version of combine-change-calls-1, the buffer is seen as
modified.

I'm not sure but I imagine it has something to do with the lack of
timestamp in buffer-undo-list created by combine-change-calls-1.