Author: Charles Fulton
MDL-64528 core_completion: prevent toggling completion in frozen context
http://git.moodle.org/gw?p=moodle.git;a=commit;h=7868aab181eb24174a158141cce67f2ab8f43e18
http://github.com/moodle/moodle/commit/7868aab181eb24174a158141cce67f2ab8f43e18
+ 3.7 en [course:togglecompletion,core_role]