I did this, first let me remark that the docstring states:
"Insert a VC commit log message by looking at the ChangeLog.
The idea is to write your ChangeLog entries first, and then use this
command to commit your changes with that log."
So that seems to suggest that only vc-commands are covered but not the ones in
which you start the VCS command from the command line and change then
emacsclient into vc-hg-log-edit-mode
In any case edebug resulted in
(interactive "P")
(save-excursion
(let ((eoh (save-excursion (rfc822-goto-eoh) (point))))
(when (<= (point) eoh)
(goto-char eoh)
(if (looking-at "\n") (forward-char 1))))
(let ((author
(let ((log-edit-changelog-use-first
(or use-first (eq last-command 'log-edit-insert-changelog))))
(log-edit-insert-changelog-entries (log-edit-files)))))
^nil
So log-edit-files return nil!
I tried to debug this as well,
(defun log-edit-files ()
"Return the list of files that are about to be committed."
(ignore-errors (funcall log-edit-listfun)))
but again (funcall log-edit-listfun))) returned nil.
In a «normal vc-next-action that funcall returns a non nil value
Any suggestions?