test/rails_app/app/controllers/application_controller.rb in devise-2.1.4 vs test/rails_app/app/controllers/application_controller.rb in devise-2.2.0.rc

@@ -3,6 +3,7 @@
 
 class ApplicationController < ActionController::Base
   protect_from_forgery
   before_filter :current_user, :unless => :devise_controller?
   before_filter :authenticate_user!, :if => :devise_controller?
+  respond_to *Mime::SET.map(&:to_sym)
 end