Author: Zig Tan
MDL-58702 backup: Fix restoration of role mappings labels
Changes:
- Add logic to retrieve all the existing current roles.
- Apply the backup's role shortname by matching on the archetype.
- Added backup lang string 'undefinedrolemapping'.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e689e4d446013bdbf96530ab3b17ac9dae3cc87b
http://github.com/moodle/moodle/commit/e689e4d446013bdbf96530ab3b17ac9dae3cc87b
+ 3.6 en [undefinedrolemapping,core_backup]