zeroconf: notify the Zeroconf threads when hg exits Zeroconf launches two threads in the background, and they wait on Condition objects to exit. We need to call Zeroconf.close() to release those conditions so that threads can gracefully exit. This means that an interrupt on the hg process will now gracefully propagate to the Zeroconf children, fixing that bug which did not allow us to kill an `hg serve` process.