Author: sam marshall
MDL-60943 core_search: Improve exception for preg_replace errors
http://git.moodle.org/gw?p=moodle.git;a=commit;h=d20ec3606b0c9d51df07970d107b1b6c7ad2cd67
http://github.com/moodle/moodle/commit/d20ec3606b0c9d51df07970d107b1b6c7ad2cd67
+ 3.5 en [error_indexing,core_search]