This is another python3 numpy thing:

Python3:
```
(Pdb) np.unique([u'foo', 1, 1])
*** TypeError: unorderable types: str() < int()
```

Python 2.7.4:
```
numpy.unique([u'foo', 1, 1])
array([u'1', u'foo'], 
      dtype='<U3')
```