Author: Cameron Ball
MDL-73293 core_task: Cleanup stale adhoc task metadata
http://git.moodle.org/gw?p=moodle.git;a=commit;h=cd1a7291eaf814b1276f6f1a1e5e2cd7864861b1
http://github.com/moodle/moodle/commit/cd1a7291eaf814b1276f6f1a1e5e2cd7864861b1
+ 4.1 en [tasklockcleanuptask,core_admin]