QListWidget scrolls incorrectly when there are hidden items

Compile and run the attached source (or run the Python script, which uses PyQt). The list widget does not exhibit expected behavior when scrolling with the keyboard (arrow keys, PgUp/PgDown, Home/End), instead appearing to jump around randomly.

However, if the last item is selected and the up arrow key held, the list eventually starts jumping upward by multiples of 9, leading me to believe that the widget is confused about indices when there are hidden items. E.g., when going up from the item labeled 30 to the item labeled 27 (which are the 30th and 27th items inserted but are adjacent in the view because 28 and 29 are hidden) it instead goes up from the 30th visible item to the 27th visible item, thus jumping from the item labeled 90 to the item labeled 81.

This bug was present in previous versions of Qt at least a few months ago, but I don't know the version numbers.