Seems it installs 3.3 for pypy.

wheel requires Python '>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*' but the running Python is 3.3.5

It's a bit more complicated. So CPython builds success as well as PyPy3 build, but environment for PyPy (2) fails to set up.
I think we need another tox image or another layout i.e. using different images for different python versions. Or maybe open a ticket at https://github.com/themattrix/docker-tox

Looks like it sets up 3.3 for PyPy (2) build.

Could we maybe remove it from tox.ini for now? At least we'll have some checks until we fix that.

@podshumok Bump! Shall we just drop py26 for now and add pypy and pypy3 separately?

Well, we don't actually use it in CI so we can either kill it all or just change tox config to anything we find useful