qcut fails with labels=True
The docs say that `qcut()` takes either a list or a boolean as its `labels` argument. The argument is `None` by default. This, which I would have expected to give me the standard set of labels -- like None -- errors:

```python
pd.qcut(range(5), 4, labels=True)

```

This may well be expected behavior, but it does strike me as semantically weird.