tests: Add a test for read-only disks
tests: Add a test for read-only disks

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

pcdummy/lxd,pcdummy/lxd,atxwebs/lxd,Skarlso/lxd,pcdummy/lxd,lxc/lxd,Skarlso/lxd,atxwebs/lxd,stgraber/lxd,lxc/lxd,mjeanson/lxd,techtonik/lxd,atxwebs/lxd,mjeanson/lxd,jsavikko/lxd,erikmack/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,jsavikko/lxd,stgraber/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,techtonik/lxd,atxwebs/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,mjeanson/lxd,hallyn/lxd,stgraber/lxd,erikmack/lxd,Skarlso/lxd,Skarlso/lxd,techtonik/lxd,jsavikko/lxd,erikmack/lxd