Git merges in Moodle 3.5.13 by Adrian Greeve

commit 3f86f7028cc22d5d501711de67d3aadb4254450e
Author: Adrian Greeve <abgreeve@gmail.com>
Date:   Thu, 21 May 2020 08:33:31 +0800
Tag:    v3.5.13

Merge branch 'MDL-68733_35' of https://github.com/timhunt/moodle into MOODLE_35_STABLE