From d5f353ec8dc823dcaf24f927e0648b1891b9cebc Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Fri, 6 Nov 2015 11:07:11 +0200
Subject: [PATCH] Issue #24726: Revert setting the value on the dict if
 _odict_add_new_node() fails.

---
 Objects/odictobject.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Objects/odictobject.c b/Objects/odictobject.c
index 7a3ded09e6b..98cbf9496dc 100644
--- a/Objects/odictobject.c
+++ b/Objects/odictobject.c
@@ -1721,7 +1721,13 @@ PyODict_SetItem(PyObject *od, PyObject *key, PyObject *value) {
     int res = PyDict_SetItem(od, key, value);
     if (res == 0) {
         res = _odict_add_new_node((PyODictObject *)od, key);
-        /* XXX Revert setting the value on the dict? */
+        if (res < 0) {
+            /* Revert setting the value on the dict */
+            PyObject *exc, *val, *tb;
+            PyErr_Fetch(&exc, &val, &tb);
+            (void) PyDict_DelItem(od, key);
+            _PyErr_ChainExceptions(exc, val, tb);
+        }
     }
     return res;
 };