Index: Lib/test/pickletester.py
===================================================================
--- Lib/test/pickletester.py	(revision 82908)
+++ Lib/test/pickletester.py	(working copy)
@@ -384,6 +384,8 @@
 class AbstractPickleTests(unittest.TestCase):
     # Subclass must define self.dumps, self.loads.
 
+    fast = False        # Whether we should be testing the fast mode
+
     _testdata = create_data()
 
     def setUp(self):
@@ -873,6 +875,36 @@
         self.assertEqual(x.foo, y.foo)
         self.assertEqual(x.bar, y.bar)
 
+    def test_stdreducecycle(self):
+        # Fast mode doesn't support cycles.
+        if self.fast:
+            return
+
+        # Test standard __reduce__ implementations (reduce_2 in
+        # typeobject.c and _reduce_ex in copy_reg.py). Using the no-op
+        # subclasses is necessary to make those functions used instead
+        # of going through the pickle implementation's special
+        # handling of builtin types.
+
+        # Simple cycles
+        L = MyList()
+        L.append(L)
+        d = MyDict()
+        d[0] = d
+        for proto in protocols:
+            newL = self.loads(self.dumps(L, proto))
+            self.failUnless(newL[0] is newL)
+            newd = self.loads(self.dumps(d, proto))
+            self.failUnless(d[0] is d)
+
+        # More steps (this puts memoize in the cyclic path)
+        obj = MyList()
+        d = {'obj': obj}
+        obj.append(d)
+        for proto in protocols:
+            new = self.loads(self.dumps(obj, proto))
+            self.failUnless(new[0]['obj'] is new)
+
     def test_reduce_overrides_default_reduce_ex(self):
         for proto in protocols:
             x = REX_one()
@@ -1000,6 +1032,21 @@
         self.assertEqual(dumped, DATA6)
 
 
+    def test_reduce_cycle(self):
+        for proto in protocols:
+            x = REX_four()
+            try:
+                self.dumps(x, proto)
+            except Exception as e:
+                # XXX: Need reference to real PicklingError
+                exceps = 'PicklingError',
+                if self.fast:
+                    exceps += 'ValueError',
+                if e.__class__.__name__ not in exceps:
+                    raise
+            else:
+                self.fail("successfully pickled with reduce cycle")
+
 # Test classes for reduce_ex
 
 class REX_one(object):
@@ -1038,6 +1085,10 @@
         return object.__reduce__(self)
     # This one used to fail with infinite recursion
 
+class REX_four(object):
+    def __reduce__(self):
+        return REX_four, (self,)
+
 # Test classes for newobj
 
 class MyInt(int):