THRIFT-3726 Fix incorrect conditional in TMultiplexedProtocol.py

This closes #661
diff --git a/lib/py/src/TMultiplexedProcessor.py b/lib/py/src/TMultiplexedProcessor.py
index 581214b..605aa1f 100644
--- a/lib/py/src/TMultiplexedProcessor.py
+++ b/lib/py/src/TMultiplexedProcessor.py
@@ -30,7 +30,7 @@
 
     def process(self, iprot, oprot):
         (name, type, seqid) = iprot.readMessageBegin()
-        if type != TMessageType.CALL & type != TMessageType.ONEWAY:
+        if type != TMessageType.CALL and type != TMessageType.ONEWAY:
             raise TException("TMultiplex protocol only supports CALL & ONEWAY")
 
         index = name.find(TMultiplexedProtocol.SEPARATOR)