### mgrid doesn't work

Hello!
I type in sage notebook 5.8 on my local computer:

```
import numpy as np
np.mgrid?
....
example:
>>> np.mgrid[-1:1:5j]
array([-1. , -0.5, 0. , 0.5, 1. ])
```

But when I type in my notebook:

```
np.mgrid[-1:1:5j]
```

and press shift-enter, I get mistake:
TypeError: Unable to convert -0.200000000000000*I to float; use abs() or real_part() as desired

It seems to me it's the bug...