of course it works as you already noticed in your latest post; I've been using that solution for over 2 years as you can see here: https://github.com/collective/collective.prettydate/blob/master/.travis.yml
in general, most of the time I skip testing for Plone 4.0 as is really hard to keep compatibility with it unless your add-on is really simple.
I had problems in the past with
bootstrap.py but keeping it updated in the latest version solved them all. I tried also different approaches but they seemed less reliable overall and I don't want to deal with different ways of doing things.
travis.cfg configuration was a hack @datakurre developed before the Travis CI container-based infrastructure was available. it's totally unnecessary right now and adds overhead to the simple process of having just one buildout configuration for development and CI.
it must be removed from
bobtemplates.plone as is not a best practice at all.