Author: Eric Merrill
MDL-29905 question: Try to delete unused hidden/random questions
Before going to display the warning about moving in use questions,
try to delete unused Random qtype questions, as well as 'hidden'
questions (these are questions that were deleted from the category),
but were in use at the time.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=54640aba8a01d51304b36b245ee1fd90b8a7b534
http://github.com/moodle/moodle/commit/54640aba8a01d51304b36b245ee1fd90b8a7b534
+ 3.1 en [categorymove,core_question]