I just checked your code using check50 and here is the results

:) outdated.py exists  
:) input of 9/8/1636 outputs 1636-09-08  
:) input of September 8, 1636 outputs 1636-09-08  
:) input of 10/9/1701 outputs 1701-10-09  
:) input of October 9, 1701 outputs 1701-10-09  
:) input of " 9/8/1636 " outputs 1636-09-08  
:) input of 23/6/1912 results in reprompt  
:) input of 10 December, 1815 results in reprompt  
:) input of October/9/1701 results in reprompt  
:) input of 1/50/2000 results in reprompt  
:) input of December 80, 1980 results in reprompt  
:) input of September 8 1636 results in reprompt

so what is the problem?