default locale

Imported from a comment discussion on https://ru.stackoverflow.com/questions/745352/%d0%9e%d1%88%d0%b8%d0%b1%d0%ba%d0%b0-%d0%b2%d1%8b%d1%85%d0%be%d0%b4%d0%b0-%d0%b7%d0%b0-%d0%bf%d1%80%d0%b5%d0%b4%d0%b5%d0%bb%d1%8b-%d0%bc%d0%b0%d1%81%d1%81%d0%b8%d0%b2%d0%b0

http://math.stackexchange.com/q/472227/2218