stream.finished readonly doesn't fire if writable side is open

Version: master (b53cae3, 14-pre)
Platform: mac
Subsystem: stream

stream.finished(duplex, { readable: true, writable: false }, cb) doesn't fire if writable side is finalising.

const stream = require('stream')

const dup = new stream.Duplex({
  final (cb) { }, // never close writable side for test purpose
  read () {
    this.push(null)
  }
})

dup.on('end', function () {
  console.log('end fired')
})

stream.finished(dup, { readable: true, writable: false }, function () {
  // doesn't fire in master
  console.log('not readable')
})

dup.end()
dup.resume()