Do Content-negotiation for Cached Content

The action_cache plugin broke our content-negotiation.
Fixed.

app/controllers/application.rb

@@ -144,6 +144,8 @@ class ApplicationController < ActionController::Base
     end
   end
 
+  public
+
   def set_content_type_header
     if %w(atom_with_content atom_with_headlines).include?(action_name)
       response.headers['Content-Type'] = 'application/atom+xml; charset=UTF-8'
@@ -158,6 +160,8 @@ class ApplicationController < ActionController::Base
     end
   end
 
+  protected
+
   def set_robots_metatag
     if controller_name == 'wiki' and %w(show published).include? action_name 
       @robots_metatag_value = 'index,follow'

vendor/plugins/action_cache/lib/action_cache.rb

@@ -141,6 +141,7 @@ module ActionController
         def send_cached_response(cache_entry, controller)
           controller.logger.info "Send #{body_name(controller)} by response.body"
           controller.response.headers = cache_entry.headers
+          controller.set_content_type_header
           controller.response.body = fragment_body(controller)
         end