Enable bionic build replacing xenail Enable bionic 18.04 replacing xenial 16.04. Curl https://oligarchy.co.uk/xapian/ is failing to validate the SSL cert with the CA on xenial. See if this fixes it. Python 3.4 is not supported on bionic is obsolete so remove testing. It was retained because 3.4 was EPEL version for centos 7. With centos demise, removed it from 'python:' settings. Test latest 2.x release, earliest 3.x release supported by bionic (3.6), last two production 3.x releases and nightly to cut down on cost of testing. Also run tests in 3.x series in reverse order so 3.9 runs first. Hence we fail early as newest pythons seem to have more issues with the code.