Code review comment for lp://qastaging/~tchaypo/testscenarios/testcase-mixin

Ok, this is broadly fine, module the horrible horrible fact of copy in paste when in fact you want boom-tish to parameterise the tests to test with different unittest base classes.

Martin's module-parameteriser will help with that, so I'll review and merge this after that lands, which will be after testtools gets the needed support. Be a couple of days I imagine.