Git commits in Moodle 3.1.0 by Alexandru Elisei

commit b6d12864141b0280f4dd4f54ffa31e7892bd90e2
Author: Alexandru Elisei <alexandru.elisei@gmail.com>
Date:   Fri, 04 Mar 2016 21:43:36 +0800
Tag:    v3.1.0-beta

MDL-52574 accesslib: Prevent get_role_users() fail in certain cases