py.test is not needed on old plattforms

[guettli]

It is available there, too.

[plaindocs]

Thanks for reporting.

We're taking a more detailed look at this in #982 and am not quite sure what the ideal fix is yet. Any comments welcome on that issue.

[guettli]

Yes, I was wrong. The pytest is available in my virtualenv. But it is not available in the travis environment.

Please add this to the travis environment. This would make the integration of travis a bit more straight forward.

Here is my test which fails on travis because pytest is missing: https://travis-ci.org/guettli/compare-with-remote/jobs/210979841