need a genconfig gate

[Brian Rosmaita]

With zuul3, it should be possible for us to have an automated gate job that regenerates the config files. It would be good for 2 reasons:

1 - prevent bugs like https://bugs.launchpad.net/glance/+bug/1748399 from slipping through

2 - could maybe also compare the generated configs to the current ones, and propose a patch if necessary

That would be cool and would allow us to keep the default configs in etc/ up-to-date

[Brian Rosmaita (brian-rosmaita)]

Also looks like this would have caught https://review.openstack.org/#/c/597427/

But ... we may not need to do this ourselves. Doug says "the new check job we'll be adding when we switch everyone to the py3 packaging jobs over should prevent something like this".