Future works weirdly on my machine, is it a bug?

Question

someCalc := method(
  wait(2)
  return 10
)

futureResult := @someCalc

"waiting for result" println

futureResult println

"done" println

I think this code should output

waiting for result
10
done

But it output

waiting for result
10
done
done

My environment is m1x mbp, io 20151111 runs by Rosetta 2.

I don't whether it's a bug of io, or there is something I misunderstood.