old_contents: from __future__ import with_statement
  import os
  import re
  import pytz
  
  _cache_tz = None
  
  def _get_localzone():
      tzname = os.popen("systemsetup -gettimezone").read().replace("Time Zone: ", "").strip()
      if not tzname or tzname not in pytz.all_timezones_set:
          # link will be something like /usr/share/zoneinfo/America/Los_Angeles.
          link = os.readlink("/etc/localtime")
          tzname = link[link.rfind('/', 0, link.rfind('/'))+1:]
      return pytz.timezone(tzname)
  
  def get_localzone():
      """Get the computers configured local timezone, if any."""
      global _cache_tz
      if _cache_tz is None:
          _cache_tz = _get_localzone()
      return _cache_tz
  
  def reload_localzone():
      """Reload the cached localzone. You need to call this if the timezone has changed."""
      global _cache_tz
      _cache_tz = _get_localzone()
      return _cache_tz
      
  
new_contents: from __future__ import with_statement
  import os
  import re
  import pytz
  
  _cache_tz = None
  
  def _get_localzone():
      tzname = os.popen("systemsetup -gettimezone").read().replace("Time Zone: ", "").strip()
      if not tzname or tzname not in pytz.all_timezones_set:
          # link will be something like /usr/share/zoneinfo/America/Los_Angeles.
          link = os.readlink("/etc/localtime")
          tzname = link[link.rfind("zoneinfo/") + 9:]
      return pytz.timezone(tzname)
  
  def get_localzone():
      """Get the computers configured local timezone, if any."""
      global _cache_tz
      if _cache_tz is None:
          _cache_tz = _get_localzone()
      return _cache_tz
  
  def reload_localzone():
      """Reload the cached localzone. You need to call this if the timezone has changed."""
      global _cache_tz
      _cache_tz = _get_localzone()
      return _cache_tz
  
  
subject: fix macosx issue with buenos_aires timezone