I know how to do this the other way around... it would be:
>>> dt.rfc822() \'Sun, 09 Mar 1997 13:45:00 -0500\'
If you strip off the time zone, you can do it like this:
datetime.datetime.strptime('Sun, 09 Mar 1997 13:45:00', '%a, %d %b %Y %H:%M:%S')