Changes 54857 and 54840 broke code and were reverted in Py2.5 just before
it was released, but that reversion never made it to the Py2.6 head.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 1035e5f..3b7c128 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1406,7 +1406,7 @@
 		return -1;
 	}
 	mp = (PyDictObject*)a;
-	if (PyDict_CheckExact(b)) {
+	if (PyDict_Check(b)) {
 		other = (PyDictObject*)b;
 		if (other == mp || other->ma_used == 0)
 			/* a.update(a) or a.update({}); nothing to do */
diff --git a/Objects/setobject.c b/Objects/setobject.c
index bb49b67..c8db7ce 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -912,7 +912,7 @@
 {
 	PyObject *key, *it;
 
-	if (PyAnySet_CheckExact(other))
+	if (PyAnySet_Check(other))
 		return set_merge(so, other);
 
 	if (PyDict_CheckExact(other)) {
@@ -1207,7 +1207,7 @@
 	if (result == NULL)
 		return NULL;
 
-	if (PyAnySet_CheckExact(other)) {		
+	if (PyAnySet_Check(other)) {		
 		Py_ssize_t pos = 0;
 		setentry *entry;
 
@@ -1398,7 +1398,7 @@
 	if ((PyObject *)so == other)
 		return set_clear_internal(so);
 	
-	if (PyAnySet_CheckExact(other)) {
+	if (PyAnySet_Check(other)) {
 		setentry *entry;
 		Py_ssize_t pos = 0;
 
@@ -1447,7 +1447,7 @@
 	setentry *entry;
 	Py_ssize_t pos = 0;
 
-	if (!PyAnySet_CheckExact(other)  && !PyDict_CheckExact(other)) {
+	if (!PyAnySet_Check(other)  && !PyDict_CheckExact(other)) {
 		result = set_copy(so);
 		if (result == NULL)
 			return NULL;
@@ -1554,7 +1554,7 @@
 		Py_RETURN_NONE;
 	}
 
-	if (PyAnySet_CheckExact(other)) {
+	if (PyAnySet_Check(other)) {
 		Py_INCREF(other);
 		otherset = (PySetObject *)other;
 	} else {
@@ -1637,7 +1637,7 @@
 	setentry *entry;
 	Py_ssize_t pos = 0;
 
-	if (!PyAnySet_CheckExact(other)) {
+	if (!PyAnySet_Check(other)) {
 		PyObject *tmp, *result;
 		tmp = make_new_set(&PySet_Type, other);
 		if (tmp == NULL)
@@ -1666,7 +1666,7 @@
 {
 	PyObject *tmp, *result;
 
-	if (!PyAnySet_CheckExact(other)) {
+	if (!PyAnySet_Check(other)) {
 		tmp = make_new_set(&PySet_Type, other);
 		if (tmp == NULL)
 			return NULL;