Update:
It looks like some new firewall rules that are introduced in newer
versions of trunk are stopping IPv6 from working.
I turned off Allow-MLD, and 2 blank rules which seem to be there by
factory default accept forward any esp and any udp port 500. Also
disabled SYN flood protection an
Further to this, I have compiled trunk versions 47750 and 47458 which
both exhibit the same IPv6 non-routing issue, however with 47458 the
IPv6 address is a bit less b0rked...
inet6 addr: :::::561e:7d31:631e%3/64 Scope:Global
PING ipv6.google.com(sin04s05-in-x0e.1e100.net)