Segfault on mlab import

Hi everyone,

I have been trying to get mayavi to work with python 3 on an up to date arch linux system using conda virtual environments.

I tried what was posted in one of the issues:
1. `conda create -n oldqt python=3 pyqt=4`
2. `. activate oldqt`
3. `conda install -c menpo mayavi`

then I enter Ipython and execute each of the following commands:
```py
import os
os.environ["QT_API"] = "pyqt"
%gui qt
from mayavi import mlab
```

When executing the last command it just crashes and prints:
`[1] 23813 segmentation fault (core dumped) ipython`

just fyi if it helps:
```
$pacman -Q | grep qt

attica-qt5 5.35.0-1
libdbusmenu-qt5 0.9.3+16.04.20160218-1
phonon-qt5 4.9.1-4
phonon-qt5-vlc 0.9.1-2
polkit-qt5 0.112.0+git20160226-1
pyqt5-common 5.8.2-4
python-pyqt5 5.8.2-4
qt4 4.8.7-20
qt5-base 5.9.1-2
qt5-declarative 5.9.1-2
qt5-location 5.9.1-2
qt5-multimedia 5.9.1-2
qt5-script 5.9.1-2
qt5-sensors 5.9.1-2
qt5-speech 5.9.1-2
qt5-svg 5.9.1-2
qt5-tools 5.9.1-3
qt5-webchannel 5.9.1-2
qt5-webkit 5.212.0alpha2-4
qt5-x11extras 5.9.1-2
qt5-xmlpatterns 5.9.1-2
```