Developer credits
Git commits in Moodle 2.5.0 by Mike Churchward
commit d750d41e66583ce2b10decc5c6f7bde9cecf724d Author: Mike Churchward <mike@remote-learner.net> Date: Wed, 17 Apr 2013 22:48:32 +0800 Tag: v2.5.0-rc1 MDL-34933 core_message: Adding index to improve database access on message_working table.