Git commits in Moodle 3.1.13 by David Monllao

commit 7696a8d9e3f98bc3ea9289ed44a7887c89536b94
Author: David Monllao <davidm@moodle.com>
Date:   Thu, 24 May 2018 16:45:51 +0800
Tag:    v3.1.13

weekly release 3.1.12+