Merge pull request #3278 from arunagw/rails_rake_task_warning

Global variable `$rails_rake_task' not initialized Warning removed

railties/lib/rails/application/finisher.rb

@@ -2,6 +2,7 @@ module Rails
   class Application
     module Finisher
       include Initializable
+      $rails_rake_task = nil
 
       initializer :add_generator_templates do
         config.generators.templates.unshift(*paths["lib/templates"].existent)