Problem peering to nodes that have auto-tethering on

[GalRogozinski]

Bug description

When node A connects to a neighbor, it will remove it from the reconnect pool. If the neighbor was an old pre-1.8.0 node the removal from the reconnect pool will still happen.

If the neighbor will upgrade his node to 1.8.0, but will count on auto-tethering to help A connect to it, he will fail. Because A won't send connection requests and neither will the neighbor since it relies on auto-tethering and does not know A

Note that if the neighbor upgrades before A, all will work just fine! No bug will appear.

IRI version

1.8.0

Steps To Reproduce

1. You have 2 nodes A (1.8.0) and B (1.7.1) Both are off.
2. Configure A to be B as a neighbors by adding it to NEIGHBORS in the config file(iota.ini or iri.ini).
3. Turn both nodes on and wait for a hand shake fail message to appear in the log of Node A.
4. Turn off node B and upgrade it to 1.8.0.
5. Configure B to have AUTO_TETHERING_ENABLED = true and remove A from its neighbors list.
6. Start node B.

Expected behaviour

Nodes should peer

Actual behaviour

Nodes don't peer

Temporary Remedy

The operator of node A should restart. This will reinitiate a connection request to B.