pydata/pandas — pull request #8739 by jreback (2014-11-05 20:39:06+00:00)
Title: BUG: Bug in slicing a multi-index level with an empty-list (GH8737)

closes #8737

```
In [5]: multi_index = pd.MultiIndex.from_product((['foo', 'bar', 'baz'], ['alpha', 'beta']))

In [6]: df = DataFrame(np.random.randn(5, 6), index=range(5), columns=multi_index).sortlevel(0,axis=1)

In [7]: df
Out[7]:
bar baz foo
alpha beta alpha beta alpha beta
0 -0.725086 -0.715498 1.141087 -0.586018 0.906581 -0.260218
1 -1.111794 -0.393149 2.101567 0.648850 0.366892 0.554206
2 1.258239 1.472659 -0.174970 -0.355639 -0.843127 1.101716
3 -0.775790 0.419361 -0.521444 1.245519 0.759791 0.183877
4 -0.001001 -1.526741 -1.721501 0.527531 0.407099 -0.415245

In [8]: df.loc[:, ([], slice(None))]
Out[8]:
Empty DataFrame
Columns: []
Index: [0, 1, 2, 3, 4]

In [9]: df.loc[:, ([], slice(None))].columns
Out[9]:
MultiIndex(levels=[[u'bar', u'baz', u'foo'], [u'alpha', u'beta']],
labels=[[], []])
```