Except that it is necessitated by (what appears to be) a bug in `hsplit`:
```python
>>> np.hsplit(np.array([True]), [0,1])
[array([], dtype=float64), array([ True], dtype=bool), array([], dtype=float64)]
```
(in 1.8.0)

This leads to "IndexError: arrays used as indices must be of integer (or boolean) type". `astype(bool)` will stay.