Datepicker: onSelect called twice when date selected with enter key

The onSelect function is called twice in the following cases:

• When no date was previously selected, and a date is selected with the enter key
• When a date was previously selected, and a new date is selected by moving onto it keyboard interaction and pressing the enter key

If the date is selected by clicking on it with the mouse, onSelect is only called once in all these cases.

Example to demonstrate with alerts: http://jsfiddle.net/my1ade6t/