Duplicate custom field names when using non-ascii characters

I use CiviCRM in Russian language.

If I create custom field (or field set) with name in Russian and then create another with different Russian name I get an error saying this custom field name already in use. Looking into the database I see that internal name for the first field is blank. I think this is because non-ascii characters are just thrown away when creating internal name from the label.

I can overcome this by adding some unique ascii string to the field label, but this is not the best soultion I think since it adds ascii garbage to CiviCRM screens and headers in exoprted table. Also error message saying you have already defined field with some name when you certainly know you didn't is very confusing.