AUI DatePicker does not work in IE9

Picker doesn't insert a date if input field is empty.

How to reproduce in IE9:
1. Click on Create -> Blog Post
2. Click into the Posting Date input field
3. Click on the X (clear input)
4. Click on a date
5. DatePicker disappears but there is no date

Workaround

Not clearing the input seems to allow the date picker to work as expected.