message: Fix missing error string format.
diff: @@ -158,7 +158,7 @@ def shutdown_tpu_system(cluster_resolver=None):
  tpu_name = compat.as_text(cluster_resolver._tpu) # pylint: disable=protected-access
  if tpu_name not in _INITIALIZED_TPU_SYSTEMS:
  logging.warning("You are shutting down a TPU system %s that has not been "
  - "initialized.")
  + "initialized." % tpu_name)
  logging.info("Shutting down the TPU system: %s", tpu_name)
  