node:child_process spawn() stream pipe write callbacks are not invoked

[cfal]

What version of Bun is running?

1.0

What platform is your computer?

Linux x86_64

What steps can reproduce the bug?

import child_process from 'child_process';

const p = child_process.spawn(
  'cat',
  {
    stdio: ['pipe', 'pipe', 'pipe'],
  }
);

p.stdin.write('hello', () => {
  console.log('flushed!');
});

$ node childproc.js  
flushed!

$ bun childproc.js
[no output]

What is the expected behavior?

write() callbacks are invoked

What do you see instead?

No response

Additional information

No response