segmentio/analytics.js — pull request #166 by sbisker (2013-05-31 00:44:10+00:00)
Title: mixpanel: adds $referrer and $initial_referrer aliases, fixes #165

We're looking to call .identify when cookies are cleared and a user is logged back in; to preserve referrer settings in Mixpanel People on subsequent identify calls we'd like to pass in original referrer and initial_referrer values that we're saving server-side.