Author: Davo Smith
MDL-64811 mod_assign: warn about 'Default group' submissions
http://git.moodle.org/gw?p=moodle.git;a=commit;h=74ddcaaa6fc37741bff18858ddf2f92d4a67587d
http://github.com/moodle/moodle/commit/74ddcaaa6fc37741bff18858ddf2f92d4a67587d
+ 3.8 en [ungroupedusersoptional,mod_assign]