Cannot use extended character set in Site welcome message

I set welcome message on russian, e.g. "Добро пожаловать!". After server restarting I got Setup Wizard screen.
Looking through logs I saw message that getWelcomeMessage() if failed due do invalid 2nd character in UTF-8 string (sorry cannot find those message now). The message is stored in confluence.cfg.xml in Win1251 encoding. Message was set through General Configuration page.