LetDefinitions needs to be defined on the nested instance rather than the definition of ExampleGroup

Changelog.md

@@ -1,6 +1,12 @@
 ### dev
 [full changelog](http://github.com/rspec/rspec-rails/compare/v2.13.1...master)
 
+Bug fixes
+
+* `let` definitions may override methods defined in modules brought in via
+  `config.include` in controller specs. Fixes regression introduced in 2.13.
+  (Andy Lindeman, Jon Rowe)
+
 ### 2.13.1 / 2013-04-27
 [full changelog](http://github.com/rspec/rspec-rails/compare/v2.13.0...v2.13.1)
 

features/controller_specs/controller_spec.feature

@@ -33,3 +33,26 @@ Feature: controller spec
       """
     When I run `rspec spec`
     Then the example should pass
+
+  Scenario: controller is extended with a helper module
+    Given a file named "spec/controllers/widgets_controller_spec.rb" with:
+      """ruby
+      require "spec_helper"
+
+      module MyHelper
+        def my_variable
+        end
+      end
+
+      RSpec.configure {|c| c.include MyHelper }
+
+      describe WidgetsController do
+        let(:my_variable) { 'is a value' }
+
+        describe 'something' do
+          specify { expect(my_variable).to eq 'is a value' }
+        end
+      end
+      """
+    When I run `rspec spec`
+    Then the example should pass

lib/rspec/rails/example/controller_example_group.rb

@@ -142,9 +142,11 @@ def method_missing(method, *args, &block)
       end
     end
 
-    included do
-      subject { controller }
+    def subject
+      controller
+    end
 
+    included do
       metadata[:type] = :controller
 
       before do