pandas 0.13.0 tests fail against numpy 1.8.x
several  test errors of this type when run against the maintenance/1.8.x branch of numpy.

```
ERROR: test_qcut_specify_quantiles (pandas.tools.tests.test_tile.TestCut)
  File "hashtable.pyx", line 776, in pandas.hashtable.PyObjectHashTable.unique (pandas/hashtable.c:12071)
TypeError: unhashable type: 'numpy.ndarray'

FAIL: test_series_describe_multikey (pandas.tests.test_groupby.TestGroupBy)
    assert a == b, "%s: %r != %r" % (msg.format(a,b), a, b)
AssertionError: attr is not equal [dtype]: dtype('O') != dtype('float64')
```

it seems you have coded a regression of 1.8 into the tests, it is intended to fix this in numpy 1.8.1 but now that pandas relies on it makes the situation a little tricky.

see https://github.com/numpy/numpy/pull/4109

How bad would it be for pandas if we release 1.8.1 with the regression fixed?
