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_dict.py

@@ -86,6 +86,8 @@ class DictTest(unittest.TestCase):
         class BadEq(object):
             def __eq__(self, other):
                 raise Exc()
+            def __hash__(self):
+                return 24
 
         d = {}
         d[BadEq()] = 42
@@ -397,6 +399,8 @@ class DictTest(unittest.TestCase):
         class BadCmp(object):
             def __eq__(self, other):
                 raise Exc()
+            def __hash__(self):
+                return 42
 
         d1 = {BadCmp(): 1}
         d2 = {1: 1}