vz: give nice report if network device not found
vz: give nice report if network device not found

Signed-off-by: Nikolay Shirokovskiy <7fa0e2698a05be944b362bdf5d7736c0162e16c9@virtuozzo.com>

eskultety/libvirt,jfehlig/libvirt,taget/libvirt,datto/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,crobinso/libvirt,VenkatDatta/libvirt,taget/libvirt,andreabolognani/libvirt,nertpinx/libvirt,zippy2/libvirt,jardasgit/libvirt,nertpinx/libvirt,VenkatDatta/libvirt,crobinso/libvirt,jfehlig/libvirt,eskultety/libvirt,eskultety/libvirt,zippy2/libvirt,jardasgit/libvirt,libvirt/libvirt,taget/libvirt,zippy2/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,datto/libvirt,jardasgit/libvirt,datto/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,libvirt/libvirt,VenkatDatta/libvirt,jfehlig/libvirt,libvirt/libvirt,fabianfreyer/libvirt,datto/libvirt,olafhering/libvirt,crobinso/libvirt,olafhering/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,taget/libvirt,eskultety/libvirt,taget/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,zippy2/libvirt,crobinso/libvirt,nertpinx/libvirt,andreabolognani/libvirt,eskultety/libvirt,fabianfreyer/libvirt,olafhering/libvirt,andreabolognani/libvirt,jardasgit/libvirt,nertpinx/libvirt,datto/libvirt