allow any attachment filenames

config/routes.rb

@@ -48,7 +48,7 @@ Gitlab::Application.routes.draw do
   #
   # Attachments serving
   #
-  get 'files/:type/:id/:filename' => 'files#download', constraints: { id: /\d+/, type: /[a-z]+/, filename: /[a-zA-Z.0-9_\-\+]+/ }
+  get 'files/:type/:id/:filename' => 'files#download', constraints: { id: /\d+/, type: /[a-z]+/, filename:  /.+/ }
   #
   # Admin Area