cloudsmith auth doesn't work in Cygwin bash shell

That's where python is installed, in Cygwin on Win 10. Attempting to do a ```cloudsmith auth``` generates a link (which I can authenticate against) and this message:

```Starting webserver to begin authentication ...```

I'm assuming a web browser should pop up here. I know that it's possible, because the Azure CLI does, in fact, pop up a webrowser window to authenticate against.

Is there maybe a command line option I'm missing?