UPDATE: I have filed this as bug MDL-37845 (https://tracker.moodle.org/browse/MDL-37845).
Preliminary workaround: If I in "question/type/multichoice/styles.css" remove/comment out the code
.que.multichoice .feedback .rightanswer
*{
display:inline
}
and add the code
.que.multichoice .feedback .rightanswer
script{
display:none
}
then it works fine. - But of course then the right answer will start one line under 'Correct answer:' - but that is a minor issue for me.