IPv6 access to github.com
Because github.com has no IPv6 access and I've just gotten a IPv6 only install online I could not gitsync.
So i've setup a (HAproxy) proxy at github.iserv.nl which has both a A and AAAA record to gitsync against.
Because of the SSL certificate and header rewrites http and https are difficult, but ssh and git should work fine. I could successfully clone with git://github.iserv.nl/bsdperimeter/pfsense.git over IPv6.
If any others are having issues reaching github.com over IPv6, this mayb be your fix.
I've corresponded with the Tech Support at GitHub.com over IPv6 access, and although they are working on, they can not promise anything, or when.