[tz] Ulaanbaatar Time Zone Correction

[Paul Eggert]

On 11/01/2017 11:41 AM, Brian M. Vibert wrote:
> ZoneAsia/Ulaanbaatar 7:07:32 -LMT1905 Aug
> 7:00-+071978
> 8:00Mongol+08/+09
>
> It should just be 8:00 across the board at all times.

It's OK as-is, as the "Mongol" ruleset's last rule is:

Rule    Mongol    2015    2016    -    Sep    lastSat    0:00 0    -

so that standard time is in effect for the indefinite future. True, we 
could complicate the Zone by adding another line that says just "+08", 
but the usual style is to keep the zone lines simple.

You can verify that Asia/Ulaanbaatar is OK by looking at its entry in 
to2050.tzs, a file delivered as part of the tzdb-2017c.tar.lz tarball.