Revert 53667
diff --git a/Misc/NEWS b/Misc/NEWS
index bd76c87..9a13da6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -14,6 +14,7 @@
 
 - Revert SF #1615701: dict.update() does *not* call __getitem__() or keys()
   if subclassed.  This is to remain consistent with 2.5.
+  Also revert revision 53667 with made a similar change to set.update().
 
 
 What's New in Python 2.5.1c1?
diff --git a/Objects/setobject.c b/Objects/setobject.c
index a896d93..b336fba 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;
 
@@ -1331,7 +1331,7 @@
 	if ((PyObject *)so == other)
 		return set_clear_internal(so);
 	
-	if (PyAnySet_CheckExact(other)) {
+	if (PyAnySet_Check(other)) {
 		setentry *entry;
 		Py_ssize_t pos = 0;
 
@@ -1380,7 +1380,7 @@
 	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;
@@ -1487,7 +1487,7 @@
 		Py_RETURN_NONE;
 	}
 
-	if (PyAnySet_CheckExact(other)) {
+	if (PyAnySet_Check(other)) {
 		Py_INCREF(other);
 		otherset = (PySetObject *)other;
 	} else {
@@ -1570,7 +1570,7 @@
 	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)
@@ -1599,7 +1599,7 @@
 {
 	PyObject *tmp, *result;
 
-	if (!PyAnySet_CheckExact(other)) {
+	if (!PyAnySet_Check(other)) {
 		tmp = make_new_set(&PySet_Type, other);
 		if (tmp == NULL)
 			return NULL;