Howdy everyone, We recently updated the tox pep8 and fast8 environments to default to using python3 [0] because it has stricter checks and we wanted to make sure we don't let pep8 errors get through the CI gate [1]. Because of this, you'll need the python3 and python3-dev packages in your environment in order to run tox -e[pep|fast]8. Thanks, -melanie [0] https://review.openstack.org/#/c/558648 [1] http://lists.openstack.org/pipermail/openstack-dev/2018-April/129025.html