Developer credits
Git commits in Moodle 3.6.9 by Marina Glancy
commit e972cd3ef380b09149424eba3cb6c41b9a8de0a4 Author: Marina Glancy <marina@moodle.com> Date: Wed, 04 Mar 2020 01:30:06 +0800 Tag: v3.6.9 MDL-56287 gradereport_history: Separate groups queries improved