The bug where an event was not created for closing-time-only-supplied

quizzes also existed when updating a quiz instance (not only adding)...

mod/quiz/lib.php

@@ -194,6 +194,7 @@ function quiz_update_instance($quiz) {
         $event->timestart    = $quiz->timeclose;
         $event->eventtype    = 'close';
         $event->timeduration = 0;
+        add_event($event);
     }
 
     return true;