lxd/storage/utils: Disable format detection in qemu-img info in ImageUnpack
lxd/storage/utils: Disable format detection in qemu-img info in ImageUnpack

We only use qcow2 anyway.

https://ubuntu.com/security/CVE-2015-5162

Signed-off-by: Thomas Parrott <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

hallyn/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,lxc/lxd