Re-test TBB on dual-stacked IPv6 machine
This sure looks like a scary bug: https://bugzilla.mozilla.org/show_bug.cgi?id=684893
We should find someone on a dual-stack to verify that whatever the hell "Happy Eyeballs autodetection" means, it doesn't end up allowing non-proxied IPv6 traffic. The feature sounds like some kind of testing mechanism to probe for IPv6 connectivity and fallback to IPv4 otherwise.
Since Tor uses SOCKS hostnames and only proxies IPv4 traffic right now, we probably can test this with an html page with some img tags in it with IPv6 IP addresses, and over a few different schemes for good measure.
We should then keep this page in some sort of test archive, because I imagine we'll want to keep checking on this situation periodically in the future. We might want to add in some ipv6 and 6+4 host names in the test for this reason.