node.js test fails when pipes are not closed on Windows

child.js

require('child_process').spawn(process.execPath, ['grandchild']);

// exit after 500ms
setTimeout(function() { process.exit(1); }, 500);

grandchild.js

// exit after 2s
setTimeout(function() { process.exit(0); }, 2000);

test.js

var spawn = require('child_process').spawn;
var assert = require('assert');

process.chdir(__dirname);

var start = Date.now();
var child = spawn(process.execPath, ['child']);

child.on('exit', function() {
  var elapsed = Date.now() - start;
  console.log('elapsed time to exit: %dms', elapsed);
  assert.ok(elapsed < 2000, 'expecting exit event to be emitted after less than 2s since child exits after 500ms');
	process.exit(0);
});