TST/CI: PyArrow Test Failures
Weird `pyarrow` failures going on with <a href="https://github.com/pandas-dev/pandas/commit/37e23d03e1ba2298d9df05ded69028dfac0e823e">37e23d</a>:

https://travis-ci.org/pandas-dev/pandas/jobs/276857797
https://travis-ci.org/pandas-dev/pandas/jobs/276857799

Looks unrelated to commit, so something probably went wrong with `pyarrow`

cc @jreback @jorisvandenbossche @wesm 