unique Datetime test failure (local, py2 only)
Can anyone else reproduce this? (python 2 only)

```
$ pytest pandas/tests/test_algos.py::TestUnique::test_order_of_appearance
=========================================================== test session starts ============================================================
platform darwin -- Python 2.7.14, pytest-3.3.2, py-1.5.2, pluggy-0.6.0
rootdir: /Users/taugspurger/sandbox/pandas-ip-2/pandas, inifile: setup.cfg
plugins: xdist-1.22.0, forked-0.2, hypothesis-3.38.5
collected 1 item

pandas/tests/test_algos.py F                                                                                                         [100%]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> traceback >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

self = <pandas.tests.test_algos.TestUnique object at 0x10e16aa90>

    def test_order_of_appearance(self):
        # 9346
        # light testing of guarantee of order of appearance
        # these also are the doc-examples
        result = pd.unique(Series([2, 1, 3, 3]))
        tm.assert_numpy_array_equal(result,
                                    np.array([2, 1, 3], dtype='int64'))

        result = pd.unique(Series([2] + [1] * 5))
        tm.assert_numpy_array_equal(result,
                                    np.array([2, 1], dtype='int64'))

        result = pd.unique(Series([Timestamp('20160101'),
                                   Timestamp('20160101')]))
        expected = np.array(['2016-01-01T00:00:00.000000000'],
                            dtype='datetime64[ns]')
>       tm.assert_numpy_array_equal(result, expected)

pandas/tests/test_algos.py:428:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
pandas/util/testing.py:1077: in assert_numpy_array_equal
    _raise(left, right, err_msg)
pandas/util/testing.py:1071: in _raise
    raise_assert_detail(obj, msg, left, right)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

obj = 'numpy array', message = 'numpy array values are different (100.0 %)', left = '[2015-12-31T18:00:00.000000000-0600]'
right = '[2016-01-01T00:00:00.000000000-0600]', diff = None

    def raise_assert_detail(obj, message, left, right, diff=None):
        if isinstance(left, np.ndarray):
            left = pprint_thing(left)
        elif is_categorical_dtype(left):
            left = repr(left)
        if isinstance(right, np.ndarray):
            right = pprint_thing(right)
        elif is_categorical_dtype(right):
            right = repr(right)

        msg = """{obj} are different

    {message}
    [left]:  {left}
    [right]: {right}""".format(obj=obj, message=message, left=left, right=right)

        if diff is not None:
            msg += "\n[diff]: {diff}".format(diff=diff)

>       raise AssertionError(msg)
E       AssertionError: numpy array are different
E
E       numpy array values are different (100.0 %)
E       [left]:  [2015-12-31T18:00:00.000000000-0600]
E       [right]: [2016-01-01T00:00:00.000000000-0600]

pandas/util/testing.py:1008: AssertionError

```