Autoupdate core problem (IPv6 enabled host)

Hi,

I’m having problem when auto updating core of my WP 3.6.0 on the IPv6 enabled host. The resolver resolves ww.wp.xz.cn to correct IPv6 address, the server responds, but there is no update file on the IPv6 server, so I get 404 error.

I had to manually write IPv4 address of ww.wp.xz.cn to hosts file to complete the autoupdate.

Additionally, I have the same problem with Jetpack plugin (I had to add wordpress.com IPv4 address) and Akismet.