prevent kolla-build from building images that are known not to work for a given base/type

[Christian Berendt]

In the Kolla CI gate, we build everything -- and then, if there are
errors, we match them against a list of images that are known to fail
[1].

This feels backwards, why even build things that are known to fail in
the first place ?

For example, if I do "kolla-build -b centos -t binary", it should not
even attempt to build "bifrost-base" because there's no support for
that distro/type combination.
As an end user and not a CI system using tox, I don't know what is
supported and what isn't.

[1]: https://github.com/openstack/kolla/blob/master/tests/test_build.py#L47-L85

source: http://lists.openstack.org/pipermail/openstack-dev/2017-January/110106.html

[Mark Goddard (mgoddard)]

We now have a list of unbuildable images.