Index: app/controllers/application_controller.rb
===================================================================
--- app/controllers/application_controller.rb	(revision 645)
+++ app/controllers/application_controller.rb	(working copy)
@@ -267,7 +267,8 @@
     back_url = CGI.unescape(params[:back_url].to_s)
     if !back_url.blank?
       begin
-        uri = URI.parse(back_url)
+        # Workaround for ruby bug #21314: Uri parser not accepting non-Latin characters
+        uri = URI.parse(URI.escape(back_url))
         # do not redirect user to another host or to the login or register page
         if (uri.relative? || (uri.host == request.host)) && !uri.path.match(%r{/(login|account/register)})
           redirect_to(back_url)