Ipykernel QXcbConnection: Could not connect to display
```python
import pandas as pd
df = pd.read_csv('oils.csv')
df.QXcbConnection: Could not connect to display
Aborted (core dumped)
```
#### Problem description

I was using `ipython` to run the codes above, and when I pressed `tab` after `df.` for auto-completion, it disconnected the `ipython` and showed the `QXcbConnection: Could not connect to display` error.

I am using `Python 3.6.3 :: Anaconda, Inc.`, pandas `0.20.3`, ipykernel `4.6.1`, and ipython `6.1.0`

Any advise?