This part of the code in 'question_category_object.php' 'update_category' method was used before Moodle 4.0 version for renaming
the random questions in an updated category. For Moodle 4.1, it is unnecessary as the details of random questions are no more
stored in 'question' table but in 'question_set_references' table. The method call move_question_set_references handles the same.
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