MDL-9506 MDL-9629 Added code to grade_category::delete so that its children have their categoryid/parent field updated. However, the query used sets the fields to an empty string instead of a null value. The unit test for grade_categories fails.
MDL-9506 MDL-9629 Added code to grade_category::delete so that its children have their categoryid/parent field updated. However, the query used sets the fields to an empty string instead of a null value. The unit test for grade_categories fails.

dilawar/moodle