firstWeekday is different when setting new defaultRegion

[chunxige]

extension SwiftDate {
    static func setDefaultChinaRegion(locale: Locale) {
        var calender = Calendar.autoupdatingCurrent
        calender.firstWeekday = 2
        print("calender.firstWeekday = ", calender.firstWeekday)
        defaultRegion = Region(calendar: calender,
                                         zone: Zones.asiaShanghai.toTimezone(),
                               locale: locale)
        print("defaultRegion.calendar.firstWeekday = ", defaultRegion.calendar.firstWeekday)
    }
}

output

calender.firstWeekday =  2
defaultRegion.calendar.firstWeekday =  1