Author: Mikhail Golenkov
MDL-74234 assign: Fix grading page for filtered out users
http://git.moodle.org/gw?p=moodle.git;a=commit;h=6684ca3da779bb7b29fb8e4bb3ae5b2c8f06c65f
http://github.com/moodle/moodle/commit/6684ca3da779bb7b29fb8e4bb3ae5b2c8f06c65f
+ 4.1 en [userisfilteredout,core_error]