IPv6 autoconf fails on multihomed host

/etc/network.subr has this code:

---------------
        if [ ${rtsol_available} = yes -a -n "${rtsol_interfaces}" ]; then
                # Act as endhost - automatically configured.
                # You can configure only single interface, as
                # specification assumes that autoconfigured host has
                # single interface only.
                sysctl net.inet6.ip6.accept_rtadv=1
                set ${rtsol_interfaces}
                ifconfig $1 up
                rtsol ${rtsol_flags} $1
        fi
---------------

The interfaces on our host are:
nv0 rl0 xl0 lo0

nv0 is on a local RFC1918 test network with no IPv6 connectivity,
rl0 is on our LAN with IPv6 connectivity and an IPv6 router.
Clearly, the rtsol fails.

What specification assumes that an autoconfigured host has a single
interface only?

Setting ${rtsol_flags} to "-a" does not work, because the code
above will give "rtsol -a nv0".

I think a non-forwarding host with multiple interfaces should be
supported.

Opinions?

	rvdp