message: TPUEstimator: Fix shutdown behavior after preemption.
diff: @@ -418,7 +418,7 @@ class ResetComputation(object):
  def __call__(self, run_context, all_workers, lame_workers):
  del run_context, lame_workers
  - all_workers.shutdown()
  + all_workers.shutdown(exit_code=42)
  logging.info('Resetting coordinator.')
  raise CoordinatorResetError()
  @@ -435,7 +435,7 @@ class ShutdownLameWorkers(object):
  pass
  def __call__(self, run_context, all_workers, lame_workers):
  - lame_workers.shutdown()
  + lame_workers.shutdown(exit_code=42)
  class ShutdownAllWorkers(object):
  @@ -449,4 +449,4 @@ class ShutdownAllWorkers(object):
  pass
  def __call__(self, run_context, all_workers, lame_workers):
  - all_workers.shutdown()
  + all_workers.shutdown(exit_code=42)
  