From d08a2c2576457b7d0229a00b4977044a38ad0d68 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Tue, 19 Apr 2011 10:05:03 -0700
Subject: [PATCH 1/3] Issue 11875: Keep OrderedDict's __reduce__ from
 temporarily mutating the object.

---
 Lib/collections.py | 5 ++---
 Misc/NEWS          | 3 +++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Lib/collections.py b/Lib/collections.py
index fb9464fa87e..9381f516763 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -101,10 +101,9 @@ class OrderedDict(dict):
     def __reduce__(self):
         'Return state information for pickling'
         items = [[k, self[k]] for k in self]
-        tmp = self.__map, self.__root, self.__in_repr
-        del self.__map, self.__root, self.__in_repr
         inst_dict = vars(self).copy()
-        self.__map, self.__root, self.__in_repr = tmp
+        for k in vars(self.__class__()):
+            inst_dict.pop(k, None)
         if inst_dict:
             return (self.__class__, (items,), inst_dict)
         return self.__class__, (items,)
diff --git a/Misc/NEWS b/Misc/NEWS
index c424e1eb94b..7e95d80c13f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -58,6 +58,9 @@ Library
 - Issue #11467: Fix urlparse behavior when handling urls which contains scheme
   specific part only digits. Patch by Santoso Wijaya.
 
+- Issue #11875: collections.OrderedDict's __reduce__ was temporarily
+  mutating the object instead of just working on a copy.
+
 - collections.Counter().copy() now works correctly for subclasses.
 
 - Issue #11474: Fix the bug with url2pathname() handling of '/C|/' on Windows.

From ab694380466be70294aa8e5b99b10e9f0c48b3bf Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Tue, 19 Apr 2011 10:05:53 -0700
Subject: [PATCH 2/3] Hmm, __ne__ was missing

---
 Lib/collections.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Lib/collections.py b/Lib/collections.py
index 9381f516763..5ae590763bd 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -112,6 +112,7 @@ class OrderedDict(dict):
     keys = MutableMapping.keys
     values = MutableMapping.values
     items = MutableMapping.items
+    __ne__ = MutableMapping.__ne__
 
     __marker = object()
 

From 019a97c77cc750d104adcc53ca4b84e29a069317 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Tue, 19 Apr 2011 10:21:27 -0700
Subject: [PATCH 3/3] Issue 11875: Keep OrderedDict's __reduce__ from
 temporarily mutating the object.

---
 Lib/collections.py | 5 ++---
 Misc/NEWS          | 3 +++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Lib/collections.py b/Lib/collections.py
index cde734debd9..a1f789082b5 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -154,10 +154,9 @@ class OrderedDict(dict):
     def __reduce__(self):
         'Return state information for pickling'
         items = [[k, self[k]] for k in self]
-        tmp = self.__map, self.__root, self.__hardroot
-        del self.__map, self.__root, self.__hardroot
         inst_dict = vars(self).copy()
-        self.__map, self.__root, self.__hardroot = tmp
+        for k in vars(self.__class__()):
+            inst_dict.pop(k, None)
         if inst_dict:
             return (self.__class__, (items,), inst_dict)
         return self.__class__, (items,)
diff --git a/Misc/NEWS b/Misc/NEWS
index fa8f039b82c..1885fb73cf9 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -62,6 +62,9 @@ Library
 
 - Issue #11852: Add missing imports and update tests.
 
+- Issue #11875: collections.OrderedDict's __reduce__ was temporarily
+  mutating the object instead of just working on a copy.
+
 - Issue #11467: Fix urlparse behavior when handling urls which contains scheme
   specific part only digits. Patch by Santoso Wijaya.