Issue #15535: Fix pickling of named tuples.
diff --git a/Lib/collections.py b/Lib/collections.py
index eb20243..33aedd9 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -281,6 +281,10 @@
         'Return self as a plain tuple.  Used by copy and pickle.'
         return tuple(self)
 
+    def __getstate__(self):
+        'Exclude the OrderedDict from pickling'
+        return None
+
 {field_defs}
 '''