stream/iter: merge() does not abort pending read for a single source #64444

import { merge } from 'node:stream/iter';
import { setTimeout } from 'node:timers/promises';

const source = {
  [Symbol.asyncIterator]() { return this; },
  next() { return new Promise(() => {}); },
  return() {
    console.log('source closed');
    return { done: true };
  },
};

const iterator = merge(source, {
  signal: AbortSignal.timeout(10),
})[Symbol.asyncIterator]();

console.log(await Promise.race([
  iterator.next().then(null, (error) => error.name),
  setTimeout(100, 'still pending'),
]));