Multiple SIGINT signals sent to node process while in shutdown cycle.

- Overrode the sigint listener if in the shutdown cycle. This prevents control being returned to the pty before the node process is fully halted.

lib/scaffold/start.js

@@ -153,6 +153,7 @@ function registerExitHandlers(_process, node) {
       });
     }
     if (options.sigint) {
+      _process.on('SIGINT', function(){});
       cleanShutdown(_process, node);
     }
   }