Clarify expected behaviour when breaking async iteration of teed ReadableStream

[lukasIO]

What is the issue with the Streams Standard?

Is it intended by the spec that breaking async iteration of a teed stream halts the execution of the program until all branches are cancelled?

const rs = new ReadableStream({
  start(controller) {
    let i = 0;
    const interval = setInterval(() => {
      controller.enqueue(i++);
    }, 100);

    // Clean up when canceled
    this._cancel = () => {
      clearInterval(interval);
      console.log('cancelled');
    };
  },
  cancel(reason) {
    console.log('cancel() called with', reason);
    this._cancel?.();
    return Promise.resolve();
  },
});

const [r1, r2] = rs.tee();

let i = 0;
(async () => {
  for await (const val of r1) {
    console.log('r1', val);
    if (i++ > 2) {
      console.log('breaking r1');
      break;
    }
  }
  console.log('finished r1 loop');
})();

Right now in all environments I tested in (browsers and across NodeJS versions) the last log I get is "breaking r1" - finished r1 loop never gets logged