Git commits in Moodle 3.5.5 by Dmitrii Metelkin

commit c025ce8af1d81d770d355d54bb859ee3915dbfb0
Author: Dmitrii Metelkin <dmitriim@catalyst-au.net>
Date:   Wed, 03 Oct 2018 15:13:49 +0800
Tag:    v3.5.5

MDL-63516 groups: fix unexpected debugging message