intersection on DatetimeIndex fails for empty indices of "quality"
index = pandas.DatetimeIndex(start='2000-01-01', periods=4, freq='T')
index[0:0].intersection(index)

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\dev\Python27\Lib\site-packages\pandas\tseries\index.py", line 845, in intersection
    if self[0] <= other[0]:
  File "C:\dev\Python27\Lib\site-packages\pandas\tseries\index.py", line 976, in **getitem**
    val = arr_idx[key]
IndexError: index out of bounds
