--- a/Tools/gdb/libpython.py	Sat Aug 24 20:52:45 2013 +0200
+++ b/Tools/gdb/libpython.py	Sat Aug 24 21:07:07 2013 +0200
@@ -922,21 +922,26 @@
 class PySetObjectPtr(PyObjectPtr):
     _typename = 'PySetObject'
 
+    @classmethod
+    def _dummy_key(self):
+        return gdb.lookup_global_symbol('_PySet_Dummy').value()
+
+    def __iter__(self):
+        dummy_ptr = self._dummy_key()
+        table = self.field('table')
+        for i in safe_range(self.field('mask') + 1):
+            setentry = table[i]
+            key = setentry['key']
+            if key != 0 and key != dummy_ptr:
+                yield PyObjectPtr.from_pyobject_ptr(key)
+
     def proxyval(self, visited):
         # Guard against infinite loops:
         if self.as_address() in visited:
             return ProxyAlreadyVisited('%s(...)' % self.safe_tp_name())
         visited.add(self.as_address())
 
-        members = []
-        table = self.field('table')
-        for i in safe_range(self.field('mask')+1):
-            setentry = table[i]
-            key = setentry['key']
-            if key != 0:
-                key_proxy = PyObjectPtr.from_pyobject_ptr(key).proxyval(visited)
-                if key_proxy != '<dummy key>':
-                    members.append(key_proxy)
+        members = (key.proxyval(visited) for key in self)
         if self.safe_tp_name() == 'frozenset':
             return frozenset(members)
         else:
@@ -965,18 +970,11 @@
 
         out.write('{')
         first = True
-        table = self.field('table')
-        for i in safe_range(self.field('mask')+1):
-            setentry = table[i]
-            key = setentry['key']
-            if key != 0:
-                pyop_key = PyObjectPtr.from_pyobject_ptr(key)
-                key_proxy = pyop_key.proxyval(visited) # FIXME!
-                if key_proxy != '<dummy key>':
-                    if not first:
-                        out.write(', ')
-                    first = False
-                    pyop_key.write_repr(out, visited)
+        for key in self:
+            if not first:
+                out.write(', ')
+            first = False
+            key.write_repr(out, visited)
         out.write('}')
 
         if tp_name != 'set':