message: explain better what is non-deterministic here
diff: @@ -33,5 +33,5 @@ fn is_u64_aligned(u: &Tag<u64>) -> bool {
  pub fn main() {
  let x = mk_rec();
  - is_u64_aligned(&x.t); // the result of this is non-deterministic
  + is_u64_aligned(&x.t); // the result of this is non-deterministic (even with a fixed seed, results vary between platforms)
  }
  