When figuring out the routing type for the ltmap, prune out the firewall entry in the virt_nodes table since its routertype always set to 'none'.
When figuring out the routing type for the ltmap, prune out the
firewall entry in the virt_nodes table since its routertype always set
to 'none'.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome