Git commits in Moodle 3.9.7 by Simey Lameze

commit c72839d6d06240cf515721adb93a848847cff12c
Author: Simey Lameze <simey@moodle.com>
Date:   Fri, 16 Apr 2021 11:42:33 +0800
Tag:    v3.9.7

MDL-71156 core: machinery to recover orphaned calendar events