ui.DatePicker Prev Button not working with showing multiple month and showCurrentAtPos not equal to zero

When showing more than 1 month at a time and setting showCurrentAtPos/showCurrentMonthAtPos to be anything but 0, the prev button does not operate (does nothing). Next button will properly advance, but previous has no affect. In the same case (showing multiple months) with showCurrentAtPos and showCurrentMonthAtPos set to zero the previous button works properly as expected.

<script>
$( "#datepicker" ).datepicker({
numberOfMonths: 3,
showButtonPanel: true,
showCurrentAtPos: 1,
showCurrentMonthAtPos: 1
});
</script>
<div id="datepicker"></div>