phpBB ignores/doesn't display IPv6 formatted addresses in Admin CP

I've got a board running phpBB 3.0.7-PL1, which was upgraded from 3.0.5 with the automatic updater tool. After the update, the admin CP no longer displays the IP addresses of users or admins/mods in the logs, and they aren't logged properly when a user registers. All IPs are shown as 127.0.0.1, which is the default IP specified in the new includes/session.php.

Lighttpd accepts both IPv4 and IPv6 connections, but changes IPv4 addresses into IPv6 format, i.e. ::ffff:127.0.0.1 before passing them to phpBB. All worked fine in 3.0.5, and I was able to get this function working again by replacing lines 270-291 of 3.0.7-PL1's session.php with line 270 of 3.0.5's session.php.