fix isOpen return None, to be consistent with other transport
Client: python
diff --git a/lib/py/src/transport/TTransport.py b/lib/py/src/transport/TTransport.py
index 9dbe95d..be89f4b 100644
--- a/lib/py/src/transport/TTransport.py
+++ b/lib/py/src/transport/TTransport.py
@@ -397,6 +397,8 @@
                     TTransportException.NOT_OPEN,
                     "Bad SASL negotiation status: %d (%s)"
                     % (status, challenge))
+    def isOpen(self):
+        return self.transport.isOpen()
 
     def send_sasl_msg(self, status, body):
         header = pack(">BI", status, len(body))