Revert "restored the ability to use method missing matchers like be_b…

…lank or be_true in before blocks for routing example groups"

This reverts commit c1c2f60.

Unfortunately, there is code outside rspec's control that refers
directly to the instance variable, so this change ends up breaking more
than it fixes.

- Reopens rspec#460.

lib/rspec/rails/example/routing_example_group.rb

@@ -9,10 +9,7 @@ module RoutingExampleGroup
     include RSpec::Rails::Matchers::RoutingMatchers::RouteHelpers
 
     module InstanceMethods
-
-      def routes
-        @routes ||= ::Rails.application.routes
-      end
+      attr_reader :routes
 
       private
 
@@ -23,6 +20,10 @@ def method_missing(m, *args, &block)
 
     included do
       metadata[:type] = :routing
+
+      before do
+        @routes = ::Rails.application.routes
+      end
     end
   end
 end