Git commits in Moodle 2.3.7 by Matt Petro

commit c8b33aa772aeda566c6f43892c0e46c131dd6a3c
Author: Matt Petro <petro@engr.wisc.edu>
Date:   Tue, 16 Apr 2013 19:19:23 +0800
Tag:    v2.3.7

MDL-34403 mod quiz: fix error during enrolment