Set GError even if libvirt error is unknown
Set GError even if libvirt error is unknown

JGulic/libvirt-glib,JGulic/libvirt-glib,libvirt/libvirt-glib,libvirt/libvirt-glib,JGulic/libvirt-glib,JGulic/libvirt-glib,JGulic/libvirt-glib,libvirt/libvirt-glib