Git commits in Moodle 3.9.0 by Nick Phillips

commit 7a2baafc9628598810075269bc69a3828415a064
Author: Nick Phillips <nick.phillips@otago.ac.nz>
Date:   Wed, 04 Mar 2020 11:16:41 +0800
Tag:    v3.9.0-beta

MDL-68103 theme_classic: hidden-print => d-print-none for BS4.