"May" in czech language is shown as "kvě" instead of "květen" - in mini calendar header in view module

The month name that is shown as header or title of a mini calendar created by view module shows only shortened name of month to 3 chars for May. It is not problem of translation - we set all translations to correct full name "květen". The other months are shown correctly (full name in local language). I think it is a bug.