Author: Zig Tan
MDL-33886 backup: Add backup filename length < 255 char validation
http://git.moodle.org/gw?p=moodle.git;a=commit;h=e714f3cee988efe069a2333608451f0fd558e4a4
http://github.com/moodle/moodle/commit/e714f3cee988efe069a2333608451f0fd558e4a4
+ 3.4 en [errorfilenametoolong,core_backup]