Author: Aaron Barnes
MDL-40097 completion: Make restoring grade criteria more robust
http://git.moodle.org/gw?p=moodle.git;a=commit;h=129e786cf42a57bf9becd8f56e8439d7ebe9f8db
http://github.com/moodle/moodle/commit/129e786cf42a57bf9becd8f56e8439d7ebe9f8db
+ 2.9 en [roleidnotfound,core_completion]