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=9dccff7793524e3503e7f520b2a91143a6d973f0
http://github.com/moodle/moodle/commit/9dccff7793524e3503e7f520b2a91143a6d973f0
+ 2.5 en [duplicateshortname,enrol_ldap]