Git commits in Moodle 3.5.6 by Cameron Ball

commit c55d75120a3ef6ecd600009fee6177753f78a789
Author: Cameron Ball <cameron@moodle.com>
Date:   Thu, 21 Mar 2019 16:04:37 +0800
Tag:    v3.5.6

MDL-65104 registration: Ensure $registration is always null when no record exists