vlan: T3018: vif/vif-s vlan id can not be re-used
vlan: T3018: vif/vif-s vlan id can not be re-used

In the past it was possible to configure a vif-s interface and a vif interface
both with the same VLAN ID. VyOS 1.2 reported a Kernel error:
  RTNETLINK answers: File exists
  Error creating VLAN device eth1.100
so this should not be possible at all in VyOS 1.3

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x