I don't get that:

```python
>>> x = y = np.int(0)
>>> y += 1
>>> x, y
(0, 1)
```

Gael, where you thinking of 0-d arrays?

```python
>>> x = y = array(0)
>>> x += 1
>>> x, y
(array(1), array(1))
```

I'm not sure if guarding for this is worthwhile. It's very likely that a later refactoring round undoes this; callers should take care not to produce these values.