make sure prev controller stopped before setting params

see:
#1034

lib/router_client.js

@@ -73,6 +73,13 @@ Router.prototype.dispatch = function (url, context, done) {
 
   this._currentRoute = route;
 
+
+  // even if we already have an existing controller we'll stop it
+  // and start it again. But since the actual controller instance
+  // hasn't changed, the helpers won't need to rerun.
+  if (this._currentController)
+    this._currentController.stop();
+
   //XXX Instead of this, let's consider making all RouteControllers
   //    singletons that get configured at dispatch. Will revisit this
   //    after v1.0.
@@ -86,12 +93,6 @@ Router.prototype.dispatch = function (url, context, done) {
     controller = this.createController(url, context);
   }
 
-  // even if we already have an existing controller we'll stop it
-  // and start it again. But since the actual controller instance
-  // hasn't changed, the helpers won't need to rerun.
-  if (this._currentController)
-    this._currentController.stop();
-
   this._currentController = controller;
 
   controller.dispatch(self._stack, url, function onRouterDispatchCompleted (err) {