Merge the raw data with the config file and store it.

def SaveDataToFD(self, raw_data, fd):
    """Merge the raw data with the config file and store it."""
    for key, value in iteritems(raw_data):
      # TODO(hanuszczak): Incorrect type specification for `set`.
      # pytype: disable=wrong-arg-types
      self.set("", key, value=value)
      # pytype: enable=wrong-arg-types

    self.write(fd)