Some tests fail only in py2.6: https://travis-ci.org/wikimedia/pywikibot-core/jobs/27558463 (https://gerrit.wikimedia.org/r/139591/ is an attempted fix). But I think we may instead drop support for py2.6 entirely, focusing ourselves on py2.7 ? py3k.
* no more need for external dependencies like https://gerrit.wikimedia.org/r/138318 * less work for Travis-CI * new features like dict comprehension, etc.