I don't think the patch is to blame, the only change it introduced is addition of the enable="yes" parameter to all libvirt <net/> XML definitions, which just confirms the default value in explicit terms.
What do you mean by "internal DNS"? Is libvirt's dnsmasq no longer started? That would be very weird because we still use NAT networks.
At this moment (I have just logged into VPN) I cannot resolve the host (you refer to) by name (I have two nameservers: 10.38.5.26 and 10.35.255.14, both supplied by vpnc). Can you share its address?