Author: Andrew Nicols
MDL-40975 Course: Remove groupmode when forced at course level
http://git.moodle.org/gw?p=moodle.git;a=commit;h=d881e0bb8455c203d9d9d2e9be6f9088148978bd
http://github.com/moodle/moodle/commit/d881e0bb8455c203d9d9d2e9be6f9088148978bd
- 2.6 en [forcedmodeinbrackets,core]