One issue we have in CI is reconnection races: if an incoming
connection arrives while an outgoing one is negotiated, we close the
outgoing one and issue a disconnect, which fails any connect attempts.
By sending a "reconnected" message instead of disconnect/connect we
can avoid disturbing in-progress connection attempts which happens in CI
quite a bit.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>