using 'select' to enable errors and warnings to enable which are off by default disables on by default errors and warnings
when using 'select: select errors and warnings to enable which are off by default' (https://flake8.readthedocs.org/en/latest/config.html?highlight=select) rules that aren't in the select get turned off.
For example in hacking,we select the one rule that is off by default (https://github.com/openstack-dev/hacking/blob/master/tox.ini#L41), and then all other rules appear to stop running.
I think this is because select comes from pep8 itself, and pep8's concept of select is '--select=errors select errors and warnings (e.g. E,W6)' https://pep8.readthedocs.org/en/latest/intro.html?highlight=select