[Datepicker] First or last week of the year is wrong

[Datepicker] First or last week of the year is wrong

Hi,
I have the following problem:
I have ' showWeek ' option set to ' true '. The first week of the year is shown as '52' (the last week of the previous year). You can observe this behaviour in this sample ( https://jqueryui.com/resources/demos/datepicker/show-week.html).

Steps to reproduce:
1. Open the sample
2. Navigate to January 2012
3. Take a look at the first week

Actual result:
The week number is '52'
Screenshot attached

Expected result:
The week number should be '1'

Note:
The same issue can be reproduced if you navigate to December 2014 and have a look at the last week. Its number is '1'