[libvirt] cannot set ownership on /nfs/mounted/image.iso: Operation not permitted

[Dan Kenigsberg]

I having libvirt run qemu as non-root, but I don't think libvirt should
try chowning image files. Cerntainly not if they sit on a root_squashing
nfs server.

Also, the behavior of libvirt in this regard is a bit surprising
for local image files and even for host devices. It should be enough
that an image is accessible to qemu; it does not have to be owned by it.
The fact that qemuDomainSetAllDeviceOwnership() with restore=1 does not
really restore ownership of device/file but force-chowns it to root:root
is anouther surprise.

Dan