subject is defined as a method rather than with the subject declarative method

There is currently some odd interactions between rspec-rails and
rspec-core when it comes to `let` definitions.

If we call `subject` in an `included` hook, the dynamically generated
`LetDefinitions` module gets inserted into the ancestor chain earlier
than normal. This placement no longer allows `let` definitions to
override methods defined on other modules that are brought in via
`config.include`.

We may raise a warning in future (see discussion in #738)

[Fixes #738]

Author: alindeman

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)
 

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