Git commits in Moodle 3.1.6 by Darko Miletic

commit 7bfa58873a4ebfb5ea8b25c8f33da93f834e0df0
Author: Darko Miletic <darko.miletic@gmail.com>
Date:   Mon, 20 Mar 2017 15:09:15 +0800
Tag:    v3.1.6

MDL-58079 core_enrol: Fixed invalid category tag

commit 6e0b2cde30397bfb34e2f8254c6b65d81c6d3ea4
Author: Darko Miletic <darko.miletic@gmail.com>
Date:   Fri, 17 Mar 2017 01:23:34 +0800
Tag:    v3.1.6

MDL-58079 core_enrol: Implementing fix and unit test