Add tests for bug #478115, parsedate_tz() IndexError when a Date:

field exists with an empty value.

Lib/test/test_email.py

@@ -937,6 +937,9 @@ class TestMiscellaneous(unittest.TestCase):
                 toff = time.timezone
             self.assertEqual(offset, toff)
 
+    def test_parsedate(self):
+        self.assertEqual(Utils.parsedate(''), None)
+
 
 
 # Test the iterator/generators

Lib/test/test_rfc822.py

@@ -117,6 +117,14 @@ class MessageTestCase(unittest.TestCase):
              ('', 'goit@lip.com'),
              ])
 
+        self.check(
+            'To: Some One <someone@dom.ain>\n'
+            'From: Anudder Persin <subuddy.else@dom.ain>\n'
+            'Date:\n'
+            '\n'
+            'test',
+            [('Some One', 'someone@dom.ain')])
+
         self.check(
             'To: person@dom.ain (User J. Person)\n\n',
             [('User J. Person', 'person@dom.ain')])