Developer credits
Git commits in Moodle 2.9.3 by Jetha Chan
commit ee7300f6e6c7ec6684fe2e8dc1c136c308b3df1f Author: Jetha Chan <jetha@moodle.com> Date: Thu, 02 Jul 2015 10:19:50 +0800 Tag: v2.9.3 MDL-50685 core_form: disable hidden options, don't just hide