Git merges in Moodle 3.1.9 by Eloy Lafuente (stronk7)

commit 21144b84190afe28829e92f8b2a66fd5326b5d3e
Author: Eloy Lafuente (stronk7) <stronk7@moodle.org>
Date:   Sun, 12 Nov 2017 02:29:19 +0800
Tag:    v3.1.9

Merge branch 'install_31_STABLE' of https://git.in.moodle.com/amosbot/moodle-install into MOODLE_31_STABLE