On Tue,  3 Jan 2012 14:26:04 +0100
Richard Weinberger [off-list ref] wrote:

If net.bridge.bridge-nf-call-iptables or net.bridge.bridge-nf-call-ip6tables
are set to zero xt_physdev has no effect because skb->nf_bridge has not been set up.

Signed-off-by: Richard Weinberger <richard@nod.at>

I am not sure if this is a valid configuration. The setting of sysctl is saying
"don't do iptables on bridge (since I won't be using it)" and then you are later
doing iptables and expecting the settings as if the iptables setup was being
done.

Instead, you should just enable the net.bridge.bridge-nf-call-iptables sysctl.
If a distro chooses to disable it then you may have to do it explicitly.