message: warn when cargo miri setup does not do anything
diff: @@ -172,6 +172,9 @@ fn ask(question: &str) {
  /// done all this already.
  fn setup(ask_user: bool) {
  if std::env::var("MIRI_SYSROOT").is_ok() {
  + if !ask_user {
  + println!("WARNING: MIRI_SYSROOT already set, not doing anything.")
  + }
  return;
  }
  