tests: Fix LVM test on btrfs
tests: Fix LVM test on btrfs

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

pcdummy/lxd,dustinkirkland/lxd,atxwebs/lxd,beni55/lxd,Malizor/lxd,ericsnowcurrently/lxd,Malizor/lxd,stgraber/lxd,yura-pakhuchiy/lxd,chrisglass/lxd,jumpstarter-io/lxd,rcj4747/lxd,Malizor/lxd,rrva/lxd,achanda/lxd,hallyn/lxd,stgraber/lxd,akshaykarle/lxd,benaryorg/lxd,erikmack/lxd,yura-pakhuchiy/lxd,lxc/lxd,smoser/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,jsavikko/lxd,stgraber/lxd,atxwebs/lxd,jsavikko/lxd,pcdummy/lxd,rrva/lxd,atxwebs/lxd,hallyn/lxd,ollie314/lxd,stgraber/lxd,chrisglass/lxd,akshaykarle/lxd,smoser/lxd,chrisglass/lxd,Skarlso/lxd,dustinkirkland/lxd,erikmack/lxd,georghopp/lxd,mjeanson/lxd,benaryorg/lxd,rcj4747/lxd,atxwebs/lxd,hallyn/lxd,ericsnowcurrently/lxd,ericsnowcurrently/lxd,jumpstarter-io/lxd,lxc/lxd,hallyn/lxd,mjeanson/lxd,beni55/lxd,mjeanson/lxd,lxc/lxd,beni55/lxd,mikemccracken/lxd,dustinkirkland/lxd,jensg-st/lxd,georghopp/lxd,smoser/lxd,stgraber/lxd,rrva/lxd,Skarlso/lxd,jsavikko/lxd,pcdummy/lxd,jensg-st/lxd,achanda/lxd,achanda/lxd,benaryorg/lxd,rcj4747/lxd,georghopp/lxd,sl1pm4t/lxd,jensg-st/lxd,sl1pm4t/lxd,stgraber/lxd,mikemccracken/lxd,Skarlso/lxd,lxc/lxd,techtonik/lxd,hallyn/lxd,yura-pakhuchiy/lxd,sl1pm4t/lxd,ollie314/lxd,mikemccracken/lxd,Skarlso/lxd,akshaykarle/lxd,jumpstarter-io/lxd,techtonik/lxd,lxc/lxd,ollie314/lxd,erikmack/lxd,lxc/lxd,techtonik/lxd