Author: Nitzan Bar
MDL-41259 when duplicate course shortname exists an exception is thrown and sync is aborted
http://git.moodle.org/gw?p=moodle.git;a=commit;h=1fdb431dfef333332ffc5d9178f21cfb17089b67
http://github.com/moodle/moodle/commit/1fdb431dfef333332ffc5d9178f21cfb17089b67
+ 2.4 en [duplicateshortname,enrol_ldap]