Git commits in Moodle 3.5.5 by Amaia Anabitarte

commit 15c3d7e2082ba64ca52ca40c9a9561d1d7726e01
Author: Amaia Anabitarte <amaia@moodle.com>
Date:   Wed, 19 Dec 2018 22:23:05 +0800
Tag:    v3.5.5

MDL-64385 user: Case insensitive comparison for email domains