Update pytz to 2018.6

Update the pytz library files to those from the 2018.6 release.

lib/pytz/LICENSE.txt

@@ -1,4 +1,4 @@
-Copyright (c) 2003-2009 Stuart Bishop <stuart@stuartbishop.net>
+Copyright (c) 2003-2018 Stuart Bishop <stuart@stuartbishop.net>
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),

lib/pytz/README.txt

@@ -87,13 +87,13 @@ localized time using the standard ``astimezone()`` method:
 Unfortunately using the tzinfo argument of the standard datetime
 constructors ''does not work'' with pytz for many timezones.
 
->>> datetime(2002, 10, 27, 12, 0, 0, tzinfo=amsterdam).strftime(fmt)
+>>> datetime(2002, 10, 27, 12, 0, 0, tzinfo=amsterdam).strftime(fmt)  # /!\ Does not work this way!
 '2002-10-27 12:00:00 LMT+0020'
 
 It is safe for timezones without daylight saving transitions though, such
 as UTC:
 
->>> datetime(2002, 10, 27, 12, 0, 0, tzinfo=pytz.utc).strftime(fmt)
+>>> datetime(2002, 10, 27, 12, 0, 0, tzinfo=pytz.utc).strftime(fmt)  # /!\ Not recommended except for UTC
 '2002-10-27 12:00:00 UTC+0000'
 
 The preferred way of dealing with times is to always work in UTC,
@@ -134,19 +134,21 @@ section for more details)
 >>> dt2.strftime(fmt)
 '2002-10-27 01:30:00 EST-0500'
 
-Converting between timezones also needs special attention. We also need
+Converting between timezones is more easily done, using the
-to use the ``normalize()`` method to ensure the conversion is correct.
+standard astimezone method.
 
 >>> utc_dt = utc.localize(datetime.utcfromtimestamp(1143408899))
 >>> utc_dt.strftime(fmt)
 '2006-03-26 21:34:59 UTC+0000'
 >>> au_tz = timezone('Australia/Sydney')
->>> au_dt = au_tz.normalize(utc_dt.astimezone(au_tz))
+>>> au_dt = utc_dt.astimezone(au_tz)
 >>> au_dt.strftime(fmt)
 '2006-03-27 08:34:59 AEDT+1100'
->>> utc_dt2 = utc.normalize(au_dt.astimezone(utc))
+>>> utc_dt2 = au_dt.astimezone(utc)
 >>> utc_dt2.strftime(fmt)
 '2006-03-26 21:34:59 UTC+0000'
+>>> utc_dt == utc_dt2
+True
 
 You can take shortcuts when dealing with the UTC side of timezone
 conversions. ``normalize()`` and ``localize()`` are not really
@@ -178,7 +180,7 @@ parameter to the ``utcoffset()``, ``dst()`` && ``tzname()`` methods.
 >>> ambiguous = datetime(2009, 10, 31, 23, 30)
 
 The ``is_dst`` parameter is ignored for most timestamps. It is only used
-during DST transition ambiguous periods to resulve that ambiguity.
+during DST transition ambiguous periods to resolve that ambiguity.
 
 >>> tz.utcoffset(normal, is_dst=True)
 datetime.timedelta(-1, 77400)
@@ -472,9 +474,9 @@ True
 True
 >>> 'Canada/Eastern' in common_timezones
 True
->>> 'US/Pacific-New' in all_timezones
+>>> 'Australia/Yancowinna' in all_timezones
 True
->>> 'US/Pacific-New' in common_timezones
+>>> 'Australia/Yancowinna' in common_timezones
 False
 
 Both ``common_timezones`` and ``all_timezones`` are alphabetically
@@ -510,6 +512,15 @@ Europe/Zurich
 Europe/Zurich
 
 
+Internationalization - i18n/l10n
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Pytz is an interface to the IANA database, which uses ASCII names. The `Unicode  Consortium's Unicode Locales (CLDR) <http://cldr.unicode.org>`_
+project provides translations. Thomas Khyn's
+`l18n <https://pypi.org/project/l18n/>`_ package can be used to access
+these translations from Python.
+
+
 License
 ~~~~~~~
 
@@ -527,12 +538,13 @@ Latest Versions
 
 This package will be updated after releases of the Olson timezone
 database.  The latest version can be downloaded from the `Python Package
-Index <http://pypi.python.org/pypi/pytz/>`_.  The code that is used
+Index <https://pypi.org/project/pytz/>`_.  The code that is used
 to generate this distribution is hosted on launchpad.net and available
-using the `Bazaar version control system <http://bazaar-vcs.org>`_
+using git::
-using::
 
-    bzr branch lp:pytz
+    git clone https://git.launchpad.net/pytz
+
+A mirror on github is also available at https://github.com/stub42/pytz
 
 Announcements of new releases are made on
 `Launchpad <https://launchpad.net/pytz>`_, and the
@@ -543,7 +555,7 @@ hosted there.
 Bugs, Feature Requests & Patches
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Bugs can be reported using `Launchpad <https://bugs.launchpad.net/pytz>`_.
+Bugs can be reported using `Launchpad <https://bugs.launchpad.net/pytz>`__.
 
 
 Issues & Limitations

lib/pytz/__init__.py

@@ -8,9 +8,22 @@ See the datetime section of the Python Library Reference for information
 on how to use these modules.
 '''
 
+import sys
+import datetime
+import os.path
+
+from pytz.exceptions import AmbiguousTimeError
+from pytz.exceptions import InvalidTimeError
+from pytz.exceptions import NonExistentTimeError
+from pytz.exceptions import UnknownTimeZoneError
+from pytz.lazy import LazyDict, LazyList, LazySet
+from pytz.tzinfo import unpickler, BaseTzInfo
+from pytz.tzfile import build_tzinfo
+
+
 # The IANA (nee Olson) database is updated several times a year.
-OLSON_VERSION = '2016f'
+OLSON_VERSION = '2018f'
-VERSION = '2016.6.1'  # Switching to pip compatible version numbering.
+VERSION = '2018.6'  # pip compatible version number.
 __version__ = VERSION
 
 OLSEN_VERSION = OLSON_VERSION  # Old releases had this misspelling
@@ -21,23 +34,11 @@ __all__ = [
     'NonExistentTimeError', 'UnknownTimeZoneError',
     'all_timezones', 'all_timezones_set',
     'common_timezones', 'common_timezones_set',
+    'BaseTzInfo',
 ]
 
-import sys, datetime, os.path, gettext
 
-from pytz.exceptions import AmbiguousTimeError
+if sys.version_info[0] > 2:  # Python 3.x
-from pytz.exceptions import InvalidTimeError
-from pytz.exceptions import NonExistentTimeError
-from pytz.exceptions import UnknownTimeZoneError
-from pytz.lazy import LazyDict, LazyList, LazySet
-from pytz.tzinfo import unpickler
-from pytz.tzfile import build_tzinfo, _byte_string
-
-
-try:
-    unicode
-
-except NameError: # Python 3.x
 
     # Python 3.x doesn't have unicode(), making writing code
     # for Python 2.3 and Python 3.x a pain.
@@ -52,8 +53,11 @@ except NameError: # Python 3.x
             ...
         UnicodeEncodeError: ...
         """
+        if type(s) == bytes:
+            s = s.decode('ASCII')
+        else:
             s.encode('ASCII')  # Raise an exception if not ASCII
-        return s # But return the original string - not a byte string.
+        return s  # But the string - not a byte string.
 
 else:  # Python 2.x
 
@@ -76,11 +80,18 @@ def open_resource(name):
 
     Uses the pkg_resources module if available and no standard file
     found at the calculated location.
+
+    It is possible to specify different location for zoneinfo
+    subdir by using the PYTZ_TZDATADIR environment variable.
     """
     name_parts = name.lstrip('/').split('/')
     for part in name_parts:
         if part == os.path.pardir or os.path.sep in part:
             raise ValueError('Bad path segment: %r' % part)
+    zoneinfo_dir = os.environ.get('PYTZ_TZDATADIR', None)
+    if zoneinfo_dir is not None:
+        filename = os.path.join(zoneinfo_dir, *name_parts)
+    else:
         filename = os.path.join(os.path.dirname(__file__),
                                 'zoneinfo', *name_parts)
         if not os.path.exists(filename):
@@ -106,23 +117,9 @@ def resource_exists(name):
         return False
 
 
-# Enable this when we get some translations?
-# We want an i18n API that is useful to programs using Python's gettext
-# module, as well as the Zope3 i18n package. Perhaps we should just provide
-# the POT file and translations, and leave it up to callers to make use
-# of them.
-#
-# t = gettext.translation(
-#         'pytz', os.path.join(os.path.dirname(__file__), 'locales'),
-#         fallback=True
-#         )
-# def _(timezone_name):
-#     """Translate a timezone name using the current locale, returning Unicode"""
-#     return t.ugettext(timezone_name)
-
-
 _tzinfo_cache = {}
 
+
 def timezone(zone):
     r''' Return a datetime.tzinfo implementation for the given timezone
 
@@ -192,7 +189,7 @@ ZERO = datetime.timedelta(0)
 HOUR = datetime.timedelta(hours=1)
 
 
-class UTC(datetime.tzinfo):
+class UTC(BaseTzInfo):
     """UTC
 
     Optimized UTC implementation. It unpickles using the single module global
@@ -288,7 +285,6 @@ def _p(*args):
 _p.__safe_for_unpickling__ = True
 
 
-
 class _CountryTimezoneDict(LazyDict):
     """Map ISO 3166 country code to a list of timezone names commonly used
     in that country.
@@ -418,18 +414,18 @@ def FixedOffset(offset, _tzinfos = {}):
         >>> one = FixedOffset(-330)
         >>> one
         pytz.FixedOffset(-330)
-        >>> one.utcoffset(datetime.datetime.now())
+        >>> str(one.utcoffset(datetime.datetime.now()))
-        datetime.timedelta(-1, 66600)
+        '-1 day, 18:30:00'
-        >>> one.dst(datetime.datetime.now())
+        >>> str(one.dst(datetime.datetime.now()))
-        datetime.timedelta(0)
+        '0:00:00'
 
         >>> two = FixedOffset(1380)
         >>> two
         pytz.FixedOffset(1380)
-        >>> two.utcoffset(datetime.datetime.now())
+        >>> str(two.utcoffset(datetime.datetime.now()))
-        datetime.timedelta(0, 82800)
+        '23:00:00'
-        >>> two.dst(datetime.datetime.now())
+        >>> str(two.dst(datetime.datetime.now()))
-        datetime.timedelta(0)
+        '0:00:00'
 
     The datetime.timedelta must be between the range of -1 and 1 day,
     non-inclusive.
@@ -482,14 +478,13 @@ FixedOffset.__safe_for_unpickling__ = True
 
 
 def _test():
-    import doctest, os, sys
+    import doctest
     sys.path.insert(0, os.pardir)
     import pytz
     return doctest.testmod(pytz)
 
 if __name__ == '__main__':
     _test()
-
 all_timezones = \
 ['Africa/Abidjan',
  'Africa/Accra',
@@ -676,6 +671,7 @@ all_timezones = \
  'America/Porto_Acre',
  'America/Porto_Velho',
  'America/Puerto_Rico',
+ 'America/Punta_Arenas',
  'America/Rainy_River',
  'America/Rankin_Inlet',
  'America/Recife',
@@ -731,6 +727,7 @@ all_timezones = \
  'Asia/Aqtobe',
  'Asia/Ashgabat',
  'Asia/Ashkhabad',
+ 'Asia/Atyrau',
  'Asia/Baghdad',
  'Asia/Bahrain',
  'Asia/Baku',
@@ -751,6 +748,7 @@ all_timezones = \
  'Asia/Dili',
  'Asia/Dubai',
  'Asia/Dushanbe',
+ 'Asia/Famagusta',
  'Asia/Gaza',
  'Asia/Harbin',
  'Asia/Hebron',
@@ -816,6 +814,7 @@ all_timezones = \
  'Asia/Vientiane',
  'Asia/Vladivostok',
  'Asia/Yakutsk',
+ 'Asia/Yangon',
  'Asia/Yekaterinburg',
  'Asia/Yerevan',
  'Atlantic/Azores',
@@ -861,7 +860,6 @@ all_timezones = \
  'CST6CDT',
  'Canada/Atlantic',
  'Canada/Central',
- 'Canada/East-Saskatchewan',
  'Canada/Eastern',
  'Canada/Mountain',
  'Canada/Newfoundland',
@@ -955,6 +953,7 @@ all_timezones = \
  'Europe/Samara',
  'Europe/San_Marino',
  'Europe/Sarajevo',
+ 'Europe/Saratov',
  'Europe/Simferopol',
  'Europe/Skopje',
  'Europe/Sofia',
@@ -1072,7 +1071,6 @@ all_timezones = \
  'US/Michigan',
  'US/Mountain',
  'US/Pacific',
- 'US/Pacific-New',
  'US/Samoa',
  'UTC',
  'Universal',
@@ -1252,6 +1250,7 @@ common_timezones = \
  'America/Port_of_Spain',
  'America/Porto_Velho',
  'America/Puerto_Rico',
+ 'America/Punta_Arenas',
  'America/Rainy_River',
  'America/Rankin_Inlet',
  'America/Recife',
@@ -1301,6 +1300,7 @@ common_timezones = \
  'Asia/Aqtau',
  'Asia/Aqtobe',
  'Asia/Ashgabat',
+ 'Asia/Atyrau',
  'Asia/Baghdad',
  'Asia/Bahrain',
  'Asia/Baku',
@@ -1317,6 +1317,7 @@ common_timezones = \
  'Asia/Dili',
  'Asia/Dubai',
  'Asia/Dushanbe',
+ 'Asia/Famagusta',
  'Asia/Gaza',
  'Asia/Hebron',
  'Asia/Ho_Chi_Minh',
@@ -1351,7 +1352,6 @@ common_timezones = \
  'Asia/Pyongyang',
  'Asia/Qatar',
  'Asia/Qyzylorda',
- 'Asia/Rangoon',
  'Asia/Riyadh',
  'Asia/Sakhalin',
  'Asia/Samarkand',
@@ -1372,6 +1372,7 @@ common_timezones = \
  'Asia/Vientiane',
  'Asia/Vladivostok',
  'Asia/Yakutsk',
+ 'Asia/Yangon',
  'Asia/Yekaterinburg',
  'Asia/Yerevan',
  'Atlantic/Azores',
@@ -1444,6 +1445,7 @@ common_timezones = \
  'Europe/Samara',
  'Europe/San_Marino',
  'Europe/Sarajevo',
+ 'Europe/Saratov',
  'Europe/Simferopol',
  'Europe/Skopje',
  'Europe/Sofia',
@@ -1489,7 +1491,6 @@ common_timezones = \
  'Pacific/Guadalcanal',
  'Pacific/Guam',
  'Pacific/Honolulu',
- 'Pacific/Johnston',
  'Pacific/Kiritimati',
  'Pacific/Kosrae',
  'Pacific/Kwajalein',

lib/pytz/lazy.py

@@ -1,7 +1,10 @@
 from threading import RLock
 try:
-    from UserDict import DictMixin
+    from collections.abc import Mapping as DictMixin
-except ImportError:
+except ImportError:  # Python < 3.3
+    try:
+        from UserDict import DictMixin  # Python 2
+    except ImportError:  # Python 3.0-3.3
         from collections import Mapping as DictMixin
 
 
@@ -13,6 +16,7 @@ _fill_lock = RLock()
 class LazyDict(DictMixin):
     """Dictionary populated on first use."""
     data = None
+
     def __getitem__(self, key):
         if self.data is None:
             _fill_lock.acquire()

lib/pytz/reference.py

@@ -5,12 +5,23 @@ Used for testing against as they are only correct for the years
 '''
 
 from datetime import tzinfo, timedelta, datetime
-from pytz import utc, UTC, HOUR, ZERO
+from pytz import HOUR, ZERO, UTC
+
+__all__ = [
+    'FixedOffset',
+    'LocalTimezone',
+    'USTimeZone',
+    'Eastern',
+    'Central',
+    'Mountain',
+    'Pacific',
+    'UTC'
+]
+
 
 # A class building tzinfo objects for fixed-offset time zones.
 # Note that FixedOffset(0, "UTC") is a different way to build a
 # UTC tzinfo object.
-
 class FixedOffset(tzinfo):
     """Fixed offset in minutes east from UTC."""
 
@@ -27,7 +38,6 @@ class FixedOffset(tzinfo):
     def dst(self, dt):
         return ZERO
 
-# A class capturing the platform's idea of local time.
 
 import time as _time
 
@@ -39,6 +49,8 @@ else:
 
 DSTDIFF = DSTOFFSET - STDOFFSET
 
+
+# A class capturing the platform's idea of local time.
 class LocalTimezone(tzinfo):
 
     def utcoffset(self, dt):
@@ -66,7 +78,6 @@ class LocalTimezone(tzinfo):
 
 Local = LocalTimezone()
 
-# A complete implementation of current DST rules for major US time zones.
 
 def first_sunday_on_or_after(dt):
     days_to_go = 6 - dt.weekday()
@@ -74,12 +85,15 @@ def first_sunday_on_or_after(dt):
         dt += timedelta(days_to_go)
     return dt
 
+
 # In the US, DST starts at 2am (standard time) on the first Sunday in April.
 DSTSTART = datetime(1, 4, 1, 2)
 # and ends at 2am (DST time; 1am standard time) on the last Sunday of Oct.
 # which is the first Sunday on or after Oct 25.
 DSTEND = datetime(1, 10, 25, 1)
 
+
+# A complete implementation of current DST rules for major US time zones.
 class USTimeZone(tzinfo):
 
     def __init__(self, hours, reprname, stdname, dstname):
@@ -124,4 +138,3 @@ Eastern  = USTimeZone(-5, "Eastern",  "EST", "EDT")
 Central = USTimeZone(-6, "Central", "CST", "CDT")
 Mountain = USTimeZone(-7, "Mountain", "MST", "MDT")
 Pacific = USTimeZone(-8, "Pacific", "PST", "PDT")
-

lib/pytz/tzfile.py

@@ -3,26 +3,25 @@
 $Id: tzfile.py,v 1.8 2004/06/03 00:15:24 zenzen Exp $
 '''
 
-try:
+from datetime import datetime
-    from cStringIO import StringIO
-except ImportError:
-    from io import StringIO
-from datetime import datetime, timedelta
 from struct import unpack, calcsize
 
 from pytz.tzinfo import StaticTzInfo, DstTzInfo, memorized_ttinfo
 from pytz.tzinfo import memorized_datetime, memorized_timedelta
 
+
 def _byte_string(s):
     """Cast a string or byte string to an ASCII byte string."""
     return s.encode('ASCII')
 
 _NULL = _byte_string('\0')
 
+
 def _std_string(s):
     """Cast a string or byte string to an ASCII string."""
     return str(s.decode('ASCII'))
 
+
 def build_tzinfo(zone, fp):
     head_fmt = '>4s c 15x 6l'
     head_size = calcsize(head_fmt)
@@ -133,5 +132,3 @@ if __name__ == '__main__':
     tz = build_tzinfo('US/Eastern',
                       open(os.path.join(base, 'US', 'Eastern'), 'rb'))
     pprint(tz._utc_transition_times)
-    #print tz.asPython(4)
-    #print tz.transitions_mapping

lib/pytz/tzinfo.py

@@ -13,6 +13,8 @@ from pytz.exceptions import AmbiguousTimeError, NonExistentTimeError
 __all__ = []
 
 _timedelta_cache = {}
+
+
 def memorized_timedelta(seconds):
     '''Create only one instance of each distinct timedelta'''
     try:
@@ -24,6 +26,8 @@ def memorized_timedelta(seconds):
 
 _epoch = datetime.utcfromtimestamp(0)
 _datetime_cache = {0: _epoch}
+
+
 def memorized_datetime(seconds):
     '''Create only one instance of each distinct datetime'''
     try:
@@ -36,6 +40,8 @@ def memorized_datetime(seconds):
         return dt
 
 _ttinfo_cache = {}
+
+
 def memorized_ttinfo(*args):
     '''Create only one instance of each distinct tuple'''
     try:
@@ -51,6 +57,7 @@ def memorized_ttinfo(*args):
 
 _notime = memorized_timedelta(0)
 
+
 def _to_seconds(td):
     '''Convert a timedelta to seconds'''
     return td.seconds + td.days * 24 * 60 * 60
@@ -154,12 +161,18 @@ class DstTzInfo(BaseTzInfo):
     timezone definition.
     '''
     # Overridden in subclass
-    _utc_transition_times = None # Sorted list of DST transition times in UTC
+
-    _transition_info = None # [(utcoffset, dstoffset, tzname)] corresponding
+    # Sorted list of DST transition times, UTC
-                            # to _utc_transition_times entries
+    _utc_transition_times = None
+
+    # [(utcoffset, dstoffset, tzname)] corresponding to
+    # _utc_transition_times entries
+    _transition_info = None
+
     zone = None
 
     # Set in __init__
+
     _tzinfos = None
     _dst = None  # DST offset
 
@@ -170,7 +183,8 @@ class DstTzInfo(BaseTzInfo):
         else:
             _tzinfos = {}
             self._tzinfos = _tzinfos
-            self._utcoffset, self._dst, self._tzname = self._transition_info[0]
+            self._utcoffset, self._dst, self._tzname = (
+                self._transition_info[0])
             _tzinfos[self._transition_info[0]] = self
             for inf in self._transition_info[1:]:
                 if inf not in _tzinfos:
@@ -178,8 +192,8 @@ class DstTzInfo(BaseTzInfo):
 
     def fromutc(self, dt):
         '''See datetime.tzinfo.fromutc'''
-        if (dt.tzinfo is not None
+        if (dt.tzinfo is not None and
-            and getattr(dt.tzinfo, '_tzinfos', None) is not self._tzinfos):
+                getattr(dt.tzinfo, '_tzinfos', None) is not self._tzinfos):
             raise ValueError('fromutc: dt.tzinfo is not self')
         dt = dt.replace(tzinfo=None)
         idx = max(0, bisect_right(self._utc_transition_times, dt) - 1)
@@ -337,8 +351,8 @@ class DstTzInfo(BaseTzInfo):
             # obtain the correct timezone by winding the clock back.
             else:
                 return self.localize(
-                    dt - timedelta(hours=6), is_dst=False) + timedelta(hours=6)
+                    dt - timedelta(hours=6),
-
+                    is_dst=False) + timedelta(hours=6)
 
         # If we get this far, we have multiple possible timezones - this
         # is an ambiguous case occuring during the end-of-DST transition.
@@ -351,8 +365,7 @@ class DstTzInfo(BaseTzInfo):
         # Filter out the possiblilities that don't match the requested
         # is_dst
         filtered_possible_loc_dt = [
-            p for p in possible_loc_dt
+            p for p in possible_loc_dt if bool(p.tzinfo._dst) == is_dst
-                if bool(p.tzinfo._dst) == is_dst
         ]
 
         # Hopefully we only have one possibility left. Return it.
@@ -374,7 +387,8 @@ class DstTzInfo(BaseTzInfo):
         # i.e., behave like end-of-DST transition
         dates = {}  # utc -> local
         for local_dt in filtered_possible_loc_dt:
-            utc_time = local_dt.replace(tzinfo=None) - local_dt.tzinfo._utcoffset
+            utc_time = (
+                local_dt.replace(tzinfo=None) - local_dt.tzinfo._utcoffset)
             assert utc_time not in dates
             dates[utc_time] = local_dt
         return dates[[min, max][not is_dst](dates)]
@@ -389,11 +403,11 @@ class DstTzInfo(BaseTzInfo):
         >>> tz = timezone('America/St_Johns')
         >>> ambiguous = datetime(2009, 10, 31, 23, 30)
 
-        >>> tz.utcoffset(ambiguous, is_dst=False)
+        >>> str(tz.utcoffset(ambiguous, is_dst=False))
-        datetime.timedelta(-1, 73800)
+        '-1 day, 20:30:00'
 
-        >>> tz.utcoffset(ambiguous, is_dst=True)
+        >>> str(tz.utcoffset(ambiguous, is_dst=True))
-        datetime.timedelta(-1, 77400)
+        '-1 day, 21:30:00'
 
         >>> try:
         ...     tz.utcoffset(ambiguous)
@@ -421,19 +435,19 @@ class DstTzInfo(BaseTzInfo):
 
         >>> normal = datetime(2009, 9, 1)
 
-        >>> tz.dst(normal)
+        >>> str(tz.dst(normal))
-        datetime.timedelta(0, 3600)
+        '1:00:00'
-        >>> tz.dst(normal, is_dst=False)
+        >>> str(tz.dst(normal, is_dst=False))
-        datetime.timedelta(0, 3600)
+        '1:00:00'
-        >>> tz.dst(normal, is_dst=True)
+        >>> str(tz.dst(normal, is_dst=True))
-        datetime.timedelta(0, 3600)
+        '1:00:00'
 
         >>> ambiguous = datetime(2009, 10, 31, 23, 30)
 
-        >>> tz.dst(ambiguous, is_dst=False)
+        >>> str(tz.dst(ambiguous, is_dst=False))
-        datetime.timedelta(0)
+        '0:00:00'
-        >>> tz.dst(ambiguous, is_dst=True)
+        >>> str(tz.dst(ambiguous, is_dst=True))
-        datetime.timedelta(0, 3600)
+        '1:00:00'
         >>> try:
         ...     tz.dst(ambiguous)
         ... except AmbiguousTimeError:
@@ -512,7 +526,6 @@ class DstTzInfo(BaseTzInfo):
         )
 
 
-
 def unpickler(zone, utcoffset=None, dstoffset=None, tzname=None):
     """Factory function for unpickling pytz tzinfo instances.
 
@@ -549,8 +562,8 @@ def unpickler(zone, utcoffset=None, dstoffset=None, tzname=None):
     # get changed from the initial guess by the database maintainers to
     # match reality when this information is discovered.
     for localized_tz in tz._tzinfos.values():
-        if (localized_tz._utcoffset == utcoffset
+        if (localized_tz._utcoffset == utcoffset and
-                and localized_tz._dst == dstoffset):
+                localized_tz._dst == dstoffset):
             return localized_tz
 
     # This (utcoffset, dstoffset) information has been removed from the