@@ -, +, @@ 
------------------------------------------------------------------------
--- trac/util/tests/datefmt.py	(revision 11815)
+++ trac/util/tests/datefmt.py	(revision 11816)
@@ -523,6 +523,10 @@ 
         self.assertEqual(datefmt.to_datetime(23L, tz), expected)
         self.assertEqual(datefmt.to_datetime(23.0, tz), expected)
 
+    def test_to_datetime_typeerror(self):
+        self.assertRaises(TypeError, datefmt.to_datetime, 'blah')
+        self.assertRaises(TypeError, datefmt.to_datetime, u'bl\xe1h')
+
     def test_format_datetime_utc(self):
         t = datetime.datetime(1970, 1, 1, 1, 0, 23, 0, datefmt.utc)
         expected = '1970-01-01T01:00:23Z'
--- trac/util/datefmt.py	(revision 11815)
+++ trac/util/datefmt.py	(revision 11816)
@@ -94,6 +94,8 @@ 
                     timedelta(seconds=frac + 1)
         else:
             dt = datetime.fromtimestamp(t, tz)
+    else:
+        dt = None
     if dt:
         return tz.normalize(dt)
     raise TypeError('expecting datetime, int, long, float, or None; got %s' %