Incorrect localization for calendar of "Ending date" in poll topic

Steps to reproduce:
1. Open Branch in forum and click ob the button "New Topic"
2. Select Ukrainian language
3. Click on the field "Натисність для вибору дати"

Actual result: Calendar appears with non tranlated months and days of the week into Ukrainian
Expected result: Calendar appears with months and days of the week translated into Ukrainian

Note: The same problem with Spanish localization