Running build 1426.
When using the Calendar control for the "Watched by" feature, I encounter the following.

Check "Use Purchase Date"
NOTE: I've done this to move the date closer to purchase date, rather than the current date

Click the down arrow next to the date to bring up the Calendar

Click on ANY date other than the release date.

Expected behavior: selected date is populated, Use purchase date box is unchecked
Actual behavior: date reverts to current date, Use purchase date box is unchecked