Comment 10 for bug 1704782

The extra info of the backing file info is added on "instantiating" the guest.
So even on zesty a defined guest doesn't have the section:
      <backingStore type='file' index='1'>
        <format type='qcow2'/>
        <source file='/var/lib/uvtool/libvirt/images/x-uvt-b64-Y29tLnVidW50dS5jbG91ZC5kYWlseTpzZXJ2ZXI6MTcuMTA6cHBjNjRlbCAyMDE3MDcxMw=='/>
        <backingStore/>
      </backingStore>

Only after starting it this is generated for the "live" xml content.

So it is not a uvtool issue as the base content is the same in both cases.
Yet OTOH it is also not a virt-aa-helper issue which would generate the rule if the entry would be there.
It seems that the issue is to no more auto-detect the path and adding it to the live xml is the root casue we need to find.