Unable to commit with Subversion if non-english symbols are used in comment

It is impossible to commit into SVN if, for example, russian symbols are used in comment. I see this message in this case:

svn: E000022: Commit failed (details follow):
svn: E000022: Error normalizing log message to internal format
svn: E000022: Safe data 'AAG-5002: ' was followed by non-ASCII byte 205: unable to convert to/from UTF-8
Команда «C:\Program Files (x86)\SlikSvn\bin\svn.exe» завершилась с кодом 1.

There was no this problem in QtCreator 3.2.