This site had AAAAs for a few hours back in May 2013 (I think during the switch to CloudFlare from whatever they were using before). But when accessed over IPv

This site had AAAAs for a few hours back in May 2013 (I think during the switch to CloudFlare from whatever they were using before). But when accessed over IPv6, it would just hang for a while, and dump an error message. So, presumably the HN backend can't handle IPv6 addresses in the CloudFlare HTTP headers, and rather than fix the problem, they just turned it off.