Author: David Mudrak
MDL-30271 Inform the user about the example assessment conflict, instead of throwing the exception
http://git.moodle.org/gw?p=moodle.git;a=commit;h=2dce2409846a1e48d3006c4bfe4f89490b76db52
http://github.com/moodle/moodle/commit/2dce2409846a1e48d3006c4bfe4f89490b76db52
+ 2.2 en [assessmentreferenceconflict,mod_workshop]