parsedate_tz(): Return a 1 in the tm_yday field so that the value is acceptable to Python 2.4's time.strftime(). This fix mirrors the behavior in email 3.0. That field is documented as being "not useable" so it might as well not be buggy too <wink>.
Add a test for this behavior and update a few tests that were expecting a 0 in this field. After committing I will run the entire Python 2.3 test suite to ensure this doesn't break any Python tests.