We really need our own lnprototest tests for packet-based stuff;
these message-based tests are inherently delicate and awkward.
In particular, connectd now does dev-disconnect, so the socket is not
immediately closed after a dev-disconnect command. In this case, the
WIRE_SHUTDOWN has often already been written from connectd to channeld.
But it sometimes works, too.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>