Git commits in Moodle 3.10.0 by Simon Mok

commit 1a7928173b3b54fffe98dba3d423ea2459cd9fd2
Author: Simon Mok <simonmok@outlook.com>
Date:   Mon, 12 Oct 2020 19:30:02 +0800
Tag:    v3.10.0-beta

MDL-68070 messaging: Fix error when personal notification is disabled