pep8
only sleep after `sc` reports we're still waiting

In testing, sometimes `net stop` might not stop the service, but
checking the service using `sc query` immediately afterwards reported
the service as stopped (I suspect a process scheduling issue, but have
no real evidence of that).

Changes the logic to check using `sc query` and then sleep only if we're
not stopped (as opposed to sleep, then check using `sc query`).

This results in a few different execution paths:

* `net stop` works, we exit
* `net stop` fails, `sc query` reports the service is stopped, we exit
* `net stop` fails, `sc query` reports the service is NOT stopped, we
  sleep then check again

This approach should have us sleeping only if we really need to.