SF bug #543318 (Frank J. Tobin).

In DatagramRequestHandler.setup(), the wfile initialization should be
StringIO.StringIO(), not StringIO.StringIO(slf.packet).

Bugfix candidate (all the way back to Python 1.5.2 :-).

Lib/SocketServer.py

@@ -570,7 +570,7 @@ class DatagramRequestHandler(BaseRequestHandler):
         import StringIO
         self.packet, self.socket = self.request
         self.rfile = StringIO.StringIO(self.packet)
-        self.wfile = StringIO.StringIO(self.packet)
+        self.wfile = StringIO.StringIO()
 
     def finish(self):
         self.socket.sendto(self.wfile.getvalue(), self.client_address)