Git commits in Moodle 3.9.0 by Matt Davidson

commit 887679e510590f3c6426806c90e180da284f78ef
Author: Matt Davidson <davidso1@rose-hulman.edu>
Date:   Tue, 02 Jun 2020 21:28:29 +0800
Tag:    v3.9.0-beta

MDL-68163 gradebook: add grade item duplication