machines: when receiving signals on domain interface don't add new VMs
machines: when receiving signals on domain interface don't add new VMs

Only affect the domain if existing in order to avoid race conditions
where the domain got removed after the signal was emmited.

moraleslazaro/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,martinpitt/cockpit,deryni/cockpit,cockpituous/cockpit,cockpit-project/cockpit,deryni/cockpit,mvollmer/cockpit,martinpitt/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpituous/cockpit,mvollmer/cockpit,deryni/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpituous/cockpit,martinpitt/cockpit,cockpit-project/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,deryni/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,deryni/cockpit,garrett/cockpit,mvollmer/cockpit,garrett/cockpit,martinpitt/cockpit,garrett/cockpit,garrett/cockpit,moraleslazaro/cockpit