SF #904720:  dict.update should take a 2-tuple sequence like dict.__init_
(Championed by Bob Ippolito.)

The update() method for mappings now accepts all the same argument forms
as the dict() constructor.  This includes item lists and/or keyword
arguments.
diff --git a/Lib/test/test_userdict.py b/Lib/test/test_userdict.py
index 602fd90..0ed4369 100644
--- a/Lib/test/test_userdict.py
+++ b/Lib/test/test_userdict.py
@@ -93,8 +93,12 @@
         #update
         p.update(self.reference)
         self.assertEqual(dict(p), self.reference)
+        items = p.items()
+        p = self._empty_mapping()
+        p.update(items)
+        self.assertEqual(dict(p), self.reference)
         d = self._full_mapping(self.reference)
-        #setdefaullt
+        #setdefault
         key, value = d.iteritems().next()
         knownkey, knownvalue = self.other.iteritems().next()
         self.assertEqual(d.setdefault(key, knownvalue), value)