*   `tf.contrib.estimator.InMemoryEvaluatorHook` and
        tf.estimator.experimental.InMemoryEvaluatorHook`.
    *   `tf.contrib.estimator.make_stop_at_checkpoint_step_hook` with
        `tf.estimator.experimental.make_stop_at_checkpoint_step_hook`.
    *   Expose `tf.distribute.Strategy as the new name for
        tf.contrib.distribute.DistributionStrategy.
    *   Migrate linear optimizer from contrib to core.

# WARNING: THESE OPTIONS WONT WORK IF YOU DO NOT HAVE PROPER AUTHENTICATION AND PERMISSIONS

# Use --config=tf_public_cache to try and use the TensorFlow public build cache
# to build TensorFlow. Look at ci/official/envs to find which types of jobs
# push to the cache.  For macOS, use --config=tf_public_macos_cache