Resolves: #1574758
      Rebase to tzdata-2018e
      - North Korea changed from UTC+8:30 to UTC+9 on May 5, 2018.
      - In this update, the upstream project now defaults to using
        the "vanguard" data implementation which includes negative DST offsets.
        However, we are continuing to provide the "rearguard" format
        for data which does not use negative DST offsets to provide
        better compatibility with existing tools.  We intend to transition
        to the "vanguard" data implementation in the future.