Git commits in Moodle 3.1.5 by Gergely Kún

commit 9c6cc265da0ae5707fdae7b0fdd586fbf07a4628
Author: Gergely Kún <kun.gergely@kgservermanagement.com>
Date:   Thu, 16 Feb 2017 16:03:26 +0800
Tag:    v3.1.5

MDL-56679 core: Initialise $SESSION if necessary