Tests on circle-ci currently fail with the following traceback:
ImportError while loading conftest '.../vdirsyncer/tests/conftest.py'.
tests/conftest.py:30: in
settings.suppress_health_check = [HealthCheck.too_slow]
/home/travis/virtualenv/python3.6.7/lib/python3.6/site-packages/hypothesis/_settings.py:135: in setattr
"to decorate your test instead." % (name, value)
E AttributeError: Cannot assign hypothesis.settings.suppress_health_check=[HealthCheck.too_slow] - the settings class is immutable. You can change the global default settings with settings.load_profile, or use @settings(...) to decorate your test instead.