While restoring the Moodle Features Demo course from the MOOCH hub to the latest 2.5dev, the last page of the restore displays the following notice:

Notice: Undefined variable: sillybyrefvar in .../mod/forum/backup/moodle2/restore_forum_stepslib.php on line 200

This is a regression of MDL-30102 that changed the signature of the function:

-function forum_add_discussion($discussion, $mform=null, &$message=null, $userid=null) {

+function forum_add_discussion($discussion, $mform=null, $unused=null, $userid=null) {

so that the third parameter is not passed by reference any more. As a consequence, the restore code:

$sdid = forum_add_discussion($sd, null, $sillybyrefvar, $this->task->get_userid());

throws the notice as the $sillybyrefvar is not set there.