Index: Objects/dictobject.c
===================================================================
--- Objects/dictobject.c	(revision 71388)
+++ Objects/dictobject.c	(working copy)
@@ -791,7 +791,27 @@
 	return dictresize(mp, (mp->ma_used > 50000 ? 2 : 4) * mp->ma_used);
 }
 
+/* Internal variant of PyDict_SetItem() to be used when the hash value
+   is already known and the mp object is known to be a real dict. */
+
 int
+_PyDict_SetItemWithHash(PyDictObject *mp, PyObject *key, PyObject *value, long hash)
+{
+	register Py_ssize_t n_used = mp->ma_used;
+
+	assert(key);
+	assert(value);
+	assert(mp->ma_fill <= mp->ma_mask);  /* at least one empty slot */
+	Py_INCREF(value);
+	Py_INCREF(key);
+	if (insertdict(mp, key, hash, value) != 0)
+		return -1;
+	if (!(mp->ma_used > n_used && mp->ma_fill*3 >= (mp->ma_mask+1)*2))
+		return 0;
+	return dictresize(mp, (mp->ma_used > 50000 ? 2 : 4) * mp->ma_used);
+}
+
+int
 PyDict_DelItem(PyObject *op, PyObject *key)
 {
 	register PyDictObject *mp;
@@ -1944,7 +1964,7 @@
 	val = ep->me_value;
 	if (val == NULL) {
 		val = failobj;
-		if (PyDict_SetItem((PyObject*)mp, key, failobj))
+		if (_PyDict_SetItemWithHash(mp, key, failobj, hash))
 			val = NULL;
 	}
 	Py_XINCREF(val);