It is not possible to enable DHCP client on an interface that is down. Thus
the code which enables the interface must be placed in front of assigning all
interface addresses, static or DHCP.
s the commit.
On system bootup the above condition is true but the interface does not exists,
which throws an exception, but that's legal. Simply pass the exception!
With this change VyOS boots up and configures ethernet VLAN interfaces as
expected.