Developer credits
Git commits in Moodle 2.5.7 by Ankit Agarwal
commit ec6f010b225d6beb097e11ee18f69907a7757857 Author: Ankit Agarwal <ankit@moodle.com> Date: Thu, 10 Jul 2014 17:44:59 +0800 Tag: v2.5.7 MDL-46148 qtype_calculated: low-level defence against bad formulas