message: listen for finish event in Zip
diff: @@ -50,6 +50,10 @@ class Zip extends EventEmitter {
  }
  zip.emit('error', error);
  });
  + output.on('finish', () => {
  + debug('Zip completed');
  + zip.emit('end');
  + });
  output.on('close', () => {
  debug('Zip completed');
  zip.emit('end');
  