Backport of _abccoll.py by Benjamin Arangueren, issue 1383.

With some changes of my own thrown in (e.g. backport of r58107).

Lib/test/test_abc.py

@@ -133,6 +133,20 @@ class TestABC(unittest.TestCase):
         self.failUnless(issubclass(MyInt, A))
         self.failUnless(isinstance(42, A))
 
+    def test_all_new_methods_are_called(self):
+        class A:
+            __metaclass__ = abc.ABCMeta
+        class B:
+            counter = 0
+            def __new__(cls):
+                B.counter += 1
+                return super(B, cls).__new__(cls)
+        class C(A, B):
+            pass
+        self.assertEqual(B.counter, 0)
+        C()
+        self.assertEqual(B.counter, 1)
+
 
 def test_main():
     test_support.run_unittest(TestABC)