Author: Laurent David
MDL-82357 core_courseformat: A subsection cannot move onto itself
* Subsections are considered as section and need to be prevented to
be moved into itself so to avoid infinite recursive structures.
This prevent this from happenning at a lower level (state)
http://git.moodle.org/gw?p=moodle.git;a=commit;h=aa18e063d7902be04e2cb2ee368eae550564901d
http://github.com/moodle/moodle/commit/aa18e063d7902be04e2cb2ee368eae550564901d
+ 4.5 en [subsectionmoveerror,core]