Author: Tim Hunt
MDL-32404 question export: missing error message when exporting an empty category.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b8a70832be6cb81afe7d793e87ddf1f6ebc3cb0b
http://github.com/moodle/moodle/commit/b8a70832be6cb81afe7d793e87ddf1f6ebc3cb0b
+ 2.3 en [noquestions,core_question]