minor: unnecessary call to struct.pack

Author: Mike Dirolf

pymongo/connection.py

@@ -447,7 +447,7 @@ def __send_message_on_socket(self, operation, data, sock):
  request_id = self.__increment_id()
  to_send = struct.pack("<i", 16 + len(data))
  to_send += struct.pack("<i", request_id)
- to_send += struct.pack("<i", 0) # responseTo
+ to_send += "\x00\x00\x00\x00" # responseTo
  to_send += struct.pack("<i", operation)
 
  to_send += data