Comment 5 for bug 584910

On the chance that it helps. I observed the following behavior:

in virsh

net-edit default
 ... add and entry (call this version 1)
net-destroy default
net-start default

/var/lib/libvirt/network/default.xml is changed but /var/lib/libvirt/dnsmasq/default.hostfile is NOT

net-edit default
 ... edit the MAC address on an unrelated (junk) entry (call this version 2)
net-destroy default
net-start default

Now /var/lib/libvirt/dnsmasq/default.hostfile is changed , but it reflects the file called version 1 above.

Seems to lag one version behind.