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

[trivikr]

Version

main

Platform

macOS 26.5.2

Subsystem

stream

What steps will reproduce the bug?

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'),
]));

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior? Why is that the expected behavior?

source closed
TimeoutError

As per §12.2 Stream.merge()

On cancellation (via signal or consumer break), call .return() on all active iterators and discard ready.

What do you see instead?

still pending

The pending merged read remains unsettled and source closed is never printed

Additional information

No response