I just noticed that partman-nbd doesn't detect when NBD devices are
connected or disconnected right away.

While I know what the issue is[1], the issue is pretty minor (everything
works, it's just a bit confusing), but the fix might be somewhat
involved.

Given that, I'm not sure this time of the release is the right time to
fix it anymore. I'll do it once wheezy is out the door.

[1] It's a race in the script that performs the connect or disconnect
    operation, which takes longer than the time the script which
    populates the menu needs to do its job.