fixed a bug in a loop where the script would wait for a condition that was

supposed to be signalled by other threads which were no longer running.

scripts/targets-ipv6-multicast-echo.nse

@@ -169,10 +169,12 @@ action = function()
 	end
 
 	repeat
-		condvar "wait"
 		for thread in pairs(threads) do
 			if coroutine.status(thread) == "dead" then threads[thread] = nil end
 		end
+		if ( next(threads) ) then
+			condvar "wait"
+		end
 	until next(threads) == nil
 
 	return format_output(results)