Created attachment 671530 [details, diff] this patch corrects the dnsmasq profile I have found a "bug"/typo relating to the usr.sbin.dnsmasq profile which handles leases, these typos prevent libvirt from requesting leases, as these requests get blocked as per the profile. Here is the diff that should be applied, you can test it against your current one. This patch corrects the error, making libvirt + dnsmasq networking possible :)
Thanks for the report! This looks like bug #628918, and that should be fixed in 3.0.0.