connectd: hold peer until we're interested.

Either because lightningd tells us it wants to talk, or because the peer
says something about a channel.

We also introduce a behavior change: we disconnect after a failed open.
We might want to modify this later, but we it's a side-effect of openingd
not holding onto idle connections.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/channel.c

@@ -205,6 +205,7 @@ struct open_attempt *new_channel_open_attempt(struct channel *channel)
 	oa->our_upfront_shutdown_script = NULL;
 	oa->cmd = NULL;
 	oa->aborted = false;
+	oa->open_msg = NULL;
 
 	return oa;
 }