Seems to be an issue with PyVirtualDisplay in the build

.travis.yml

@@ -18,6 +18,7 @@ install:
   - pip install --upgrade pip
   - pip install -r requirements.txt
 # - pip install pytest-faulthandler
+  - pip install PyVirtualDisplay==0.2.5
   - pip install pytest-xvfb
   - pip install pytest-cov
   - pip install pytest-qt