It's not easy to test this in core Moodle because the get_num_selected_choices function is only used to detect when the student has selected too many choices and in that case disable clearing wrong responses and displaying a message on screen. The easiest way to test this is to install Open University plugin oumultiresponse question type (see https://moodle.org/plugins/view.php?plugin=qtype_oumultiresponse ). Create an oumultiresponse question with 2 correct answers Create a quiz with settings : unlimited attempts, each attempt build on last, deferred feedback for how questions behave and last attempt grading method (all these settings are importants to trigger the bug) include the oumultiresponse question in this quiz attempt the quiz as a student on first attempt answer the question correctly submit all and finish review your attempt and verify you get the maximum grade start a second attempt don't change your response, just submit all and finish review your second attempt and verify that you still get the maximum grade (before this patch the second attempt was graded as partially correct and a "You have selected too many options." feedback was displayed)