// Report result to all other interested goroutines.
	//
	// This happens in a separate goroutine because another goroutine might have
	// acquired a copy of `client.reauthmut.ongoing` before we cleared it, but not
	// have come around to sending its request. By answering in a goroutine, we
	// can have that goroutine linger until all responseChannels have been sent.
	// When GC has collected all sendings ends of the channel, our receiving end
	// will be closed and the goroutine will end.
	go func() {
		for responseChannel := range messages {
			responseChannel <- err
		}
	}()