Hmm, __ne__ was missing
diff --git a/Lib/collections.py b/Lib/collections.py
index 9381f51..5ae5907 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -112,6 +112,7 @@
     keys = MutableMapping.keys
     values = MutableMapping.values
     items = MutableMapping.items
+    __ne__ = MutableMapping.__ne__
 
     __marker = object()