Actually, the Russian time zone change only changes the rules of those time zoned, not the geographical extent of them. Since we just return a tz id, users can

Actually, the Russian time zone change only changes the rules of those time zoned, not the geographical extent of them. Since we just return a tz id, users can just use an updated tz database (any up-to-date Linux system has this) to get the gmt offset at a particular time.