Broadcast traffic on vlans leaks into the parent interface on NetBSD-5.1

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

        Hello.  I've just noticed an issue where broadcast traffic on vlans
also shows up on the parent interface.  My environment is NetBSD-5.1/i386
with the wm(4) driver.  I'm not sure yet if the problem is specific to the
wm(4) driver or if it's a more general issue.  The bug  didn't exist in
NetBSD-4.x.
To repeat, set up a vlan in addition to the parent interface as a subnet.
Then, run dhcpd so that it can listen and hand out addresses on both
networks.  Put a dhcp client on the vlan and watch its broadcasts show up
on both the vlan and parent interfaces of the dhcp serving box.
        Has anyone else seen this issue?  Should I file a bug?
-thanks
-Brian