message: [XLA:Python:XRT] Fix missing superclass constructor invocation in XrtBackend.
diff: @@ -60,7 +60,8 @@ class XrtBackend(xla_client.Backend):
  tf_device_type: the type of TensorFlow device to use for XRT (e.g. `"TPU"`).
  """
  - def __init__(self, tf_context, tf_device_type):
  + def __init__(self, tf_context, tf_device_type, platform="tpu"):
  + super(XrtBackend, self).__init__(platform)
  self.tf_device_type = tf_device_type
  self.context = _xla.xrt.XrtContext.Create(tf_context, tf_device_type)
  