Someone was having a problem where some non-ASCII characters in the quiz. The student was typing Hebrew, but what was stored in the database was '?????'. I think this is because Moodle was not explicitly telling the web browser which character encoding to use. However, only a few students were affected.
Anyway, as a result, I made this small change (MDL-18283). This should only make things better. However, if your quizzes involve students entering non-ASCII characters, you may wish to be vigilant for a few days.
(Hmm, perhaps it would have been better if I posted this yesterday, before the weekly builds were made? Sorry.)