alexreisner/geocoder — pull request #204 by brian-ewell (2012-03-23 05:25:09+00:00)
Title: Tweaked Geocoder#ip_address? to recognize addresses prefixed with ::ffff:

This gem is awesome, however I found it to be the cause of some headache on my latest project. After some digging, I found the cause to be that geocoder doesn't route ip addresses to freegeoip if they're prefixed with "::ffff:". Freegeoip supports this prefix out of the box, so all it took to fix was this one simple tweak.