As a result, we will assign "Returning visitor" flag slightly more often. This will lead to better data accuracy.
While editing this FAQ http://piwik.org/faq/general/faq_21418/ this bug somehow became visible.
LGTM as well. @mattab have you had a look at the failing system tests? https://travis-ci.org/piwik/piwik/jobs/116619093 I can fix them in the branch before merging if ok