Merge r22584 from trunk to 5.0-stable (#39999).

git-svn-id: https://svn.redmine.org/redmine/branches/5.0-stable@22586 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/messages_controller.rb

@@ -125,6 +125,11 @@ class MessagesController < ApplicationController
       @content = +"#{ll(Setting.default_language, :text_user_wrote_in, {:value => @message.author, :link => "message##{@message.id}"})}\n> "
     end
     @content << @message.content.to_s.strip.gsub(%r{<pre>(.*?)</pre>}m, '[...]').gsub(/(\r?\n|\r\n?)/, "\n> ") + "\n\n"
+
+    respond_to do |format|
+      format.html { render_404 }
+      format.js
+    end
   end
 
   def preview