Hi,
I've just installed virt-manager 0.9.1 on a RHEL 6.2 system. This was a
fresh system, just installed.
I then used virt-manager to add a bridge. I had the bridge connect to
eth0, which was the default interface.
Then I restarted networking.
Everything worked fine except that the GATEWAY_DEV in
/etc/sysconfig/network was NOT updated, it was still pointing to eth0,
so the routing wasn't working. I replaced it with br0, restarted the
network, and everything was fine.
It seems to me that if you are replacing the gateway device, that it
should update that as well.
JBB