[test] Shorten prefix string in test_rql_role_with_unknown_vid With Python3.7, this test fails as the error message returned by rest_publish() is: <p>an error occurred while interpreting this rql directive: ObjectNotFound('toto')</p> while we previously assumed a comma after 'toto'. Fixing this by only shortening the prefix used in out.startswith().

[flake8] fix errors in cubicweb_i18ntestcube/views.py test file

[test] Pass __module__ upon instantiation of RegistrableInstance This gets rid of the deprecation warning from logilab.common.registry: DeprecationWarning: instantiate MyAFS with __module__=__name__ and solves a test error on Python 3.7.