Developer credits
Git commits in Moodle 3.7.5 by Marina Glancy
commit 6b502fbc2b76f2a129919d01e191a3f7d1095d24 Author: Marina Glancy <marina@moodle.com> Date: Wed, 04 Mar 2020 01:30:06 +0800 Tag: v3.7.5 MDL-56287 gradereport_history: Separate groups queries improved