2 files changed, 16 insertions, 8 deletions
diff --git a/actionpack/lib/action_controller/metal/rendering_controller.rb b/actionpack/lib/action_controller/metal/rendering_controller.rb
index 46a69b6b57..4da32ca1b3 100644
--- a/actionpack/lib/action_controller/metal/rendering_controller.rb
+++ b/actionpack/lib/action_controller/metal/rendering_controller.rb
@@ -8,12 +8,17 @@ module ActionController
 
     attr_accessor :hash
     def initialize(klass, formats, locale)
+      @formats, @locale = formats, locale
       @hash = [formats, locale].hash
     end
 
     alias_method :eql?, :equal?
+
+    def inspect
+      "#<HashKey -- formats: #{@formats} locale: #{@locale}>"
+    end
   end
-  
+
   module RenderingController
     extend ActiveSupport::Concern
 
@@ -25,7 +30,7 @@ module ActionController
         template_cache.clear
         super
       end
-      
+
       def template_cache
         @template_cache ||= Hash.new {|h,k| h[k] = {} }
       end
@@ -33,16 +38,19 @@ module ActionController
 
     def process_action(*)
       self.formats = request.formats.map {|x| x.to_sym}
-      Thread.current[:format_locale_key] = HashKey.get(self.class, formats, I18n.locale)
+
+      super
+    end
+
+    def _determine_template(*)
       super
     end
 
     def render(options)
+      Thread.current[:format_locale_key] = HashKey.get(self.class, formats, I18n.locale)
+
       super
-      self.content_type ||= begin
-        mime = options[:_template].mime_type
-        formats.include?(mime && mime.to_sym) || formats.include?(:all) ? mime : Mime::Type.lookup_by_extension(formats.first)
-      end.to_s
+      self.content_type ||= options[:_template].mime_type.to_s
       response_body
     end
 
diff --git a/actionpack/lib/action_controller/testing/process.rb b/actionpack/lib/action_controller/testing/process.rb
index 09b1a59254..6bc7d60d76 100644
--- a/actionpack/lib/action_controller/testing/process.rb
+++ b/actionpack/lib/action_controller/testing/process.rb
@@ -148,7 +148,7 @@ module ActionController #:nodoc:
 
     def xml_http_request(request_method, action, parameters = nil, session = nil, flash = nil)
       @request.env['HTTP_X_REQUESTED_WITH'] = 'XMLHttpRequest'
-      @request.env['HTTP_ACCEPT'] =  [Mime::JS, Mime::HTML, Mime::XML, 'text/xml', Mime::ALL].join(', ')
+      @request.env['HTTP_ACCEPT'] ||=  [Mime::JS, Mime::HTML, Mime::XML, 'text/xml', Mime::ALL].join(', ')
       returning __send__(request_method, action, parameters, session, flash) do
         @request.env.delete 'HTTP_X_REQUESTED_WITH'
         @request.env.delete 'HTTP_ACCEPT'