Error from the quiz when editing a grade item due to a missing include

When editing a grade item, I noticed that saving the changes led to a stall: a missing class definition.

Debugging the problem I found that in /mod/quiz/lib.php beginning at line 615 mod_quiz_display_options is used.

Including the locallib solved the problem, but since I'm not sure where the include was broken or whether this is a sufficient fix I'm referring the problem.

require_once($CFG->dirroot . '/mod/quiz/locallib.php');

Thanks to whoever can push this upstream. Any information that person (or anyone) wants to give me on pushing code to the core source code, please let me know.