The Final Handshake
-------------------

   After the protocol has been shut down, the final handshake is
performed.  This handshake has no real purpose, and some UUCP packages
simply drop the connection rather than do it (in fact, some will drop
the connection immediately after both sides agree to hangup, without
even closing down the protocol).

caller: `\020OOOOOO\000'
called: `\020OOOOOOO\000'
   That is, the calling UUCP sends six `O' characters and the called
UUCP replies with seven `O' characters.  Some UUCP packages always send
six `O' characters.