https://travis-ci.org/wikimedia/pywikibot-core/jobs/287962473#L967
Running cryptography-2.1.1/setup.py -q bdist_egg --dist-dir /tmp/easy_install-uhvhsp/cryptography-2.1.1/egg-dist-tmp-00na79 error: Setup script exited with error in cryptography setup command: Invalid environment marker: platform_python_implementation != 'PyPy'
They have dropped support for python 3.3 in version 2.0 of cryptography.