Revert "Match Dev/Prod parity for Index Page"

Showing welcome page in production can expose information, which should
not be visible on production if people don't override the default root
route.

This reverts commit b0caea29c2.

railties/lib/rails/application/finisher.rb

@@ -25,11 +25,9 @@ module Rails
             get '/rails/info/properties' => "rails/info#properties"
             get '/rails/info/routes'     => "rails/info#routes"
             get '/rails/info'            => "rails/info#index"
+            get '/'                      => "rails/welcome#index"
           end
         end
-        app.routes.append do
-          get '/' => "rails/welcome#index"
-        end
       end
 
       initializer :build_middleware_stack do

railties/lib/rails/templates/rails/welcome/index.html.erb

@@ -227,7 +227,7 @@
 
             <li>
               <h2>Set up a root route to replace this page</h2>
-              <p>You're seeing this page because you haven't set a root route yet.</p>
+              <p>You're seeing this page because you're running in development mode and you haven't set a root route yet.</p>
               <p>Routes are set up in <span class="filename">config/routes.rb</span>.</p>
             </li>
 

railties/test/application/routing_test.rb

@@ -60,7 +60,7 @@ module ApplicationTests
     test "rails/welcome in production" do
       app("production")
       get "/"
-      assert_equal 200, last_response.status
+      assert_equal 404, last_response.status
     end
 
     test "rails/info/routes in production" do