Issue #11875: Alter the previous fix to work better with subclasses
diff --git a/Lib/collections.py b/Lib/collections.py
index 5ae5907..79912ec 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -102,7 +102,7 @@
         'Return state information for pickling'
         items = [[k, self[k]] for k in self]
         inst_dict = vars(self).copy()
-        for k in vars(self.__class__()):
+        for k in vars(OrderedDict()):
             inst_dict.pop(k, None)
         if inst_dict:
             return (self.__class__, (items,), inst_dict)