
Build a host-host network where routing works, but the nexthop is
wrong, and therefor _updown fails to add the route, but the eroute
is created, and traffic flows encrypted one way, but not the other.

Reported by Hugh Daniel that 
1) Packets go out in the clear on the misconfigured key
2) On the rightly configured side plaintext packets are accepted

Test needs to be written.
