I think you hit a bug here.
Let me the time to check what's happen please.
EDIT: Confirmed, you hit a really stupid bug :/
I will make an hot fix as soon as possible.
Thanks for your reports and you patience.
You can (if you don't want to wait for the fix) enable the service using the -F option like this
% sudo 66-enable -F libvirtd
It should enable the libvirtd service