Git merges in Moodle 3.5.15 by Sara Arjona

commit 9a279bae03e9254f5c6ae94563460e2a4e090a61
Author: Sara Arjona <sara@moodle.com>
Date:   Fri, 09 Oct 2020 17:11:58 +0800
Tag:    v3.5.15

Merge branch 'install_35_STABLE' of https://git.in.moodle.com/amosbot/moodle-install into MOODLE_35_STABLE