CLN: pyarrow 0.6.0 compat, we need to handle back-compat on this
 /home/travis/miniconda3/envs/pandas/lib/python3.6/site-packages/pyarrow/pandas_compat.py:248: FutureWarning: timestamps_to_ms=True is deprecated
    warnings.warn('timestamps_to_ms=True is deprecated', FutureWarning)
