fix engines rake tasks

railties/lib/rails/tasks/engine.rake

@@ -67,3 +67,5 @@ def find_engine_path(path)
     find_engine_path(File.expand_path('..', path))
   end
 end
+
+Rake.application.invoke_task(:load_app)

railties/test/generators/plugin_new_generator_test.rb

@@ -159,6 +159,14 @@ def test_ensure_that_tests_works_in_full_mode
     assert_match(/1 tests, 1 assertions, 0 failures, 0 errors/, `bundle exec rake test`)
   end
 
+  def test_ensure_that_migration_tasks_work_with_mountable_option
+    run_generator [destination_root, "--mountable"]
+    FileUtils.cd destination_root
+    quietly { system 'bundle install' }
+    `bundle exec rake db:migrate`
+    assert_equal 0, $?.exitstatus
+  end
+
   def test_creating_engine_in_full_mode
     run_generator [destination_root, "--full"]
     assert_file "app/assets/javascripts/bukkits"