Without this timidity -iA -Oj prints "Couldn't start JACK device (`j')"
and does not play MIDI.

--- a/timidity/jack_a.c
+++ b/timidity/jack_a.c
@@ -513,6 +513,8 @@ static int actl_jack(int request, void *arg)
 		ringbuf_clear(&ctx->rbuf);
 		return 0;
 
+	case PM_REQ_PLAY_START:
+		return 0;
 	}
 	return -1;
 }