Git commits in Moodle 3.8.9 by Andrew Nicols

commit 39ad2de97eef0400aedc57b7fc3dd9cf5291451e
Author: Andrew Nicols <andrew@nicols.co.uk>
Date:   Tue, 23 Mar 2021 08:03:36 +0800
Tag:    v3.8.9

MDL-69256 tests: Fix random slow test failures in completion cron