Comment 8 for bug 1542984

I haven't read all of the discussion here, but in reading the bug description I came to the same conclusion as option 2 above:

2) Add a cap in the requirements for fixtures 1.2.0 of "testtools>=0.9.22,<2.0.0" and release that as 1.2.1

But yeah it's really just a problem for openstack on stable/kilo because we capped fixtures<1.3.0:

https://github.com/openstack/requirements/blob/2e4efd8f9bd451249875e47bc641d58da31f53c6/global-requirements.txt#L217

But given testtools>=2.0.0 requires fixtures>=1.3.0, it doesn't seem terrible to cap testtools<2.0.0 in a fixtures 1.2.1 release as suggested here.