Git commits in Moodle x.x.x by Rossco Hellmans

commit 383b0f95abd7f5787a5e2e3469d007a4771031f5
Author: Rossco Hellmans <rosscohellmans@catalyst-au.net>
Date:   Wed, 13 Mar 2019 09:41:13 +0800
Tag:    v3.9.0-beta

MDL-64310 backup: allow session to be released during backup/restore