Git commits in Moodle 3.3.3 by Tobias Reischmann

commit 8db207f90fbf55a3001e7b419a6b1cfe73c5c20d
Author: Tobias Reischmann <tobias.reischmann@wi.uni-muenster.de>
Date:   Thu, 17 Aug 2017 23:01:22 +0800
Tag:    v3.3.3

MDL-59854 forum: Created unique db key for forum_subscriptions