I was almost sucessful in upgrading to 1.39b

In my testing I found a problem with the DOB section of the account sign up. I'm in UK and accordingly have set the date format as dd/mm/yy.

I've updated the includes/language/english.php to reflect the format I want and I have run a check on the developers tool kit to search for any instances of either m/d/y or mm/dd/yy and nothing appears.

Any suggestions?