prevent a traceback if we've already stopProcducing...

[git-p4: depot-paths = "//depot/": change = 896]

shoutcast.py

@@ -133,7 +133,8 @@ class ShoutTransfer(shoutcast.ShoutcastClient):
 		pass
 
 	def stopProducing(self):
-		shoutcast.ShoutcastClient.stopProducing(self)
+		if self.transport is not None:
+			shoutcast.ShoutcastClient.stopProducing(self)
 		self.request = None
 		self.passback = None