THRIFT-4778: fix inheritance for protocol factories
diff --git a/lib/py/src/protocol/THeaderProtocol.py b/lib/py/src/protocol/THeaderProtocol.py
index b27a749..13982e8 100644
--- a/lib/py/src/protocol/THeaderProtocol.py
+++ b/lib/py/src/protocol/THeaderProtocol.py
@@ -19,7 +19,7 @@
 
 from thrift.protocol.TBinaryProtocol import TBinaryProtocolAccelerated
 from thrift.protocol.TCompactProtocol import TCompactProtocolAccelerated
-from thrift.protocol.TProtocol import TProtocolBase, TProtocolException
+from thrift.protocol.TProtocol import TProtocolBase, TProtocolException, TProtocolFactory
 from thrift.Thrift import TApplicationException, TMessageType
 from thrift.transport.THeaderTransport import THeaderTransport, THeaderSubprotocolID, THeaderClientType
 
@@ -217,7 +217,7 @@
         return self._protocol.readBinary()
 
 
-class THeaderProtocolFactory(object):
+class THeaderProtocolFactory(TProtocolFactory):
     def __init__(self, allowed_client_types=(THeaderClientType.HEADERS,)):
         self.allowed_client_types = allowed_client_types