The close() method is not invoked on "unpipe" when using logger.child()

[2013xile]

As the code shows

winston-transport/modern.js

Line 47 in f4be5c7

if (src === this.parent) {

It will detect if the source stream is the same as the origin upon the "unpipe" event.
However, when using logger.child(), the object is actually changed and the close() method would never be triggered.

https://github.com/winstonjs/winston/blob/debf4fad6a4ee4121904781dc83f8723be604fbe/lib/winston/logger.js#L47

Now I have to trigger the close() method manually.

  transport.once('unpipe', () => {
    transport.close();
  });

I wonder if it is an expected behavior. Thanks in advanced.