IMSG_SETUP_PEER
CASE(IMSG_SETUP_PEER);
if (imsg_compose(&a->imsgbuf, IMSG_SETUP_PEER, b->proc, b->pid, sp[0],
if (imsg_compose(&b->imsgbuf, IMSG_SETUP_PEER, a->proc, a->pid, sp[1],
case IMSG_SETUP_PEER: