swtich to returning early if to responds to call

actionpack/lib/action_dispatch/routing/mapper.rb

@@ -237,9 +237,9 @@ def app
           end
 
           def default_controller_and_action
-            if to.respond_to?(:call)
-              { }
-            else
+            hash = {}
+            return hash if to.respond_to? :call
+
             controller = default_controller
             action     = default_action
 
@@ -260,8 +260,6 @@ def default_controller_and_action
               end
             end
 
-              hash = {}
-
             if controller.is_a? Regexp
               hash[:controller] = controller
             else
@@ -278,7 +276,6 @@ def default_controller_and_action
 
             hash
           end
-          end
 
           def check_action!(action)
             unless action || segment_keys.include?(:action)