No slice viewers with nightly on Linux

I’ve just tried running nightly on Ubuntu Linux (within Parallels on Mac), and all slice viewers are blank.

In the log, I see the following messages:

SystemError: /home/kitware/Dashboards/Nightly/Slicer-0-build/Python-2.7.13/Objects/classobject.c:521: bad argument to internal function
qSlicerPythonCppAPI::instantiateClass  - [ "__init__" ] - Failed to instantiate scripted pythonqt class "__init__" 0x7f91702d9f50 
Fail to instantiate module  "__init__"