simplestreams: handle images without labels
simplestreams: handle images without labels

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

pcdummy/lxd,erikmack/lxd,atxwebs/lxd,mjeanson/lxd,ollie314/lxd,atxwebs/lxd,techtonik/lxd,Skarlso/lxd,jsavikko/lxd,mjeanson/lxd,stgraber/lxd,lxc/lxd,ollie314/lxd,stgraber/lxd,stgraber/lxd,akshaykarle/lxd,hallyn/lxd,georghopp/lxd,jsavikko/lxd,Skarlso/lxd,pcdummy/lxd,techtonik/lxd,ollie314/lxd,jsavikko/lxd,akshaykarle/lxd,georghopp/lxd,chrisglass/lxd,atxwebs/lxd,mjeanson/lxd,chrisglass/lxd,georghopp/lxd,hallyn/lxd,atxwebs/lxd,stgraber/lxd,erikmack/lxd,lxc/lxd,akshaykarle/lxd,lxc/lxd,stgraber/lxd,techtonik/lxd,Skarlso/lxd,erikmack/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,Skarlso/lxd,hallyn/lxd,pcdummy/lxd,chrisglass/lxd,lxc/lxd,hallyn/lxd,lxc/lxd