Issue 11875: Keep OrderedDict's __reduce__ from temporarily mutating the object.

1 files changed, 2 insertions, 3 deletions

diff --git a/Lib/collections.py b/Lib/collections.py
index 3c54690eb5..28a2abf44f 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -115,10 +115,9 @@ class OrderedDict(dict):
     def __reduce__(self):
         'Return state information for pickling'
         items = [[k, self[k]] for k in self]
-        tmp = self.__map, self.__root
-        del self.__map, self.__root
         inst_dict = vars(self).copy()
-        self.__map, self.__root = tmp
+        for k in vars(OrderedDict()):
+            inst_dict.pop(k, None)
         if inst_dict:
             return (self.__class__, (items,), inst_dict)
         return self.__class__, (items,)