def validate_hour_lock(time, start_time)
      h0 = starting_unit(start_time)
      h1 = time.hour
      if h0 >= h1
        h0 - h1
      else
        if dst_offset = TimeUtil.dst_change(time)
          h0 - h1 + dst_offset
        else
          24 - h1 + h0
        end
      end
    end
def validate_hour_lock(time, start_time)
      h0 = starting_unit(start_time)
      h1 = time.hour
      if h0 >= h1
        h0 - h1
      else
        if dst_offset = TimeUtil.dst_change(time)
          h0 - h1 + dst_offset
        else
          24 - h1 + h0
        end
      end
    end
Lock the hour if explicitly set by hour_of_day, but allow for the nearest
 hour during DST start to keep the correct interval.