--- _strptime.py.orig	2010-07-12 08:55:53.000000000 -0400
+++ _strptime.py	2010-07-12 09:08:32.000000000 -0400
@@ -165,12 +165,17 @@
             time.tzset()
         except AttributeError:
             pass
+        (no_saving, has_saving) = self._get_timezone()
+        self.timezone = (no_saving, has_saving)
+
+    @classmethod
+    def _get_timezone(cls):
         no_saving = frozenset(["utc", "gmt", time.tzname[0].lower()])
         if time.daylight:
             has_saving = frozenset([time.tzname[1].lower()])
         else:
             has_saving = frozenset()
-        self.timezone = (no_saving, has_saving)
+        return (no_saving, has_saving)
 
 
 class TimeRE(dict):
@@ -296,7 +301,8 @@
     """Return a time struct based on the input string and the format string."""
     global _TimeRE_cache, _regex_cache
     with _cache_lock:
-        if _getlang() != _TimeRE_cache.locale_time.lang:
+        locale_time = _TimeRE_cache.locale_time
+        if _getlang() != locale_time.lang or locale_time.timezone != locale_time._get_timezone():
             _TimeRE_cache = TimeRE()
             _regex_cache.clear()
         if len(_regex_cache) > _CACHE_MAX_SIZE: