some dikiy pizdets

console

4.1.8@2.1.5 (main)> ru = TZInfo::Country.get('RU')
=> #<TZInfo::Country: RU>
4.1.8@2.1.5 (main)> ekb = ru.zones[5]
=> #<TZInfo::TimezoneProxy: Asia/Yekaterinburg>
4.1.8@2.1.5 (main)> z = MskTimeZone.create(ekb.name, ekb.current_period.utc_offset, ekb)
=> #<MskTimeZone:0x007f82f4547a30 @name="Asia/Yekaterinburg", @utc_offset=18000, @tzinfo=#<TZInfo::TimezoneProxy: Asia/Yekaterinburg>, @current_period=nil>
4.1.8@2.1.5 (main)> z.to_s
=> "(MSK+02:00) Asia/Yekaterinburg"

MskTimeZone

class I18nTimeZone < ActiveSupport::TimeZone
  class << self
    def all
      TZInfo::Timezone.all.map do |tzinfo|
        utc_offset = tzinfo.current_period.utc_offset
        create(tzinfo.name, utc_offset, tzinfo)
      end
    end
  end

  def to_s
    "(GMT#{formatted_offset}) #{translated_name}"
  end

  protected

  def translated_name
    I18n.t(name, scope: :timezones, default: name)
  end
end


######################

class MskTimeZone < I18nTimeZone
  @@moscow_timezone = ActiveSupport::TimeZone.new('Europe/Moscow')

  class << self
    def utc_seconds_to_msk_offset(utc_seconds, colon = true)
      seconds = utc_seconds - @@moscow_timezone.utc_offset
      seconds_to_utc_offset(seconds, colon)
    end
  end

  def formatted_offset(colon=true, alternate_utc_string = nil)
    utc_offset == 0 && alternate_utc_string ||
    self.class.utc_seconds_to_msk_offset(utc_offset, colon)
  end

  def to_s
    "(MSK#{formatted_offset}) #{translated_name}"
  end
end