title: Trouble with using iloc in pandas dataframe with hierarchical index
body: <p>I'm getting this ValueError whenever I try to give a list to iloc on a dataframe with a hierarchical index.  I'm not sure if I'm doing something wrong or if this is a bug.  I haven't had any issues using iloc the same way with a non-hierarchical index.  This is using Pandas 0.12.0.</p>
  
  <pre><code>In [25]: df
  Out[25]: 
              D         E         F
  a x -1.050681 -0.084306 -1.635852 
    y  1.544577  1.594976 -0.084866
  b x  0.462529 -1.873250  1.252685
    y -0.468074  0.673112 -0.900547
  c x  0.901710 -0.432554  0.260157
    y  0.101522 -0.550223  1.389497
  
  In [26]: df.iloc[[1,3]]
  ..... snip .....
  ValueError: Buffer dtype mismatch, expected 'Python object' but got 'long'
  
  In [27]: df.iloc[range(2)]
  ...... snip .....
  ValueError: Buffer dtype mismatch, expected 'Python object' but got 'long'
  </code></pre>