Active redirect with two roadwarriors that connect road-north but re-connect north-road

- road warriors, NORTH (assigned 192.0.2.101) and then ROAD (assigned
  192.0.2.102) connect to EAST.

- a short time later they are both redirected to WEST

- both NORTH and ROAD go into revival mode, installing traps for their
  respective assigned address

  But should they?

- using impair-revival, NORTH, and then ROAD, connect to WEST

  The existing trap is turned into a block.

  Then, since the re-connect order is reversed they are each assigned
  different IP addresses vis:

	   to EAST      to WEST
  ROAD   192.0.2.101  192.0.2.102
  NORTH  192.0.2.102  192.0.2.101

  The routing code needs to remove the old block

See: redirect clueless to a changed CP IP address #1641

