Add hack to deal with warnings

We should be able to remove this once the catch-all route is gone from
AP

Author: tenderlove

actionpack/lib/action_dispatch/testing/assertions/routing.rb

@@ -10,7 +10,7 @@ module Assertions
     # Suite of assertions to test routes generated by \Rails and the handling of requests made to them.
     module RoutingAssertions
       def setup # :nodoc:
-        @routes = nil
+        @routes ||= nil
         super
       end