pandas.tests.test_graphics.TestDataFramePlots test_unsorted_index failure
``` python

======================================================================
FAIL: test_unsorted_index (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "<...>/pandas/tests/test_graphics.py", line 312, in test_unsorted_index
    tm.assert_series_equal(rs, df.y)
  File "<...>/pandas/util/testing.py", line 166, in assert_series_equal
    assert(left.dtype == right.dtype)
AssertionError

...

(Pdb) p left.dtype
dtype('int32')
(Pdb) p right.dtype
dtype('int64')
(Pdb) p pd.__version__
'0.11.0.dev-dad367e'
```
