[libvirt-users] How can I set the advertised value of MTU for virbr0 interface?

Hi all, I want to set the advertised value of MTU for virbr0 interface on a Fedora 21 host to 1454 to accommodate the installation of new VMs for testing purposes. The aforementioned host is an OpenStack VM actually, which explains the need for a lower than 1500 MTU. I noticed Pieter Hollants' patch to set dhcp-option=<number>,"<value>" for an interface, but it seems that it has not been implemented yet. Is there a possibility to have such an option? George