Add memoizing to AD::Request

actionpack/lib/action_dispatch/http/request.rb

@@ -30,6 +30,14 @@ module ActionDispatch
       METHOD
     end
 
+    def self.new(env)
+      if request = env["action_dispatch.request"] && request.instance_of?(self)
+        return request
+      end
+
+      super
+    end
+
     def key?(key)
       @env.key?(key)
     end