[pywin32-bugs] [ pywin32-Bugs-3524786 ] Conversion of UTC timestamp to localtime is wrong at STD/DST

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Bugs item #3524786, was opened at 2012-05-08 09:34
Message generated for change (Comment added) made by bmatthews27
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Category: win32timezone
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Brian Matthews (bmatthews27)
Assigned to: Jason R. Coombs (jaraco)
Summary: Conversion of UTC timestamp to localtime is wrong at STD/DST

Initial Comment:
I am not sure if this error is in TimeZoneInfo or datetime.

I am running my PC in Pacific time, so I have a way to
easily check the results. The script below converts UTC timestamps into a
datetime in the Pacific time zone. The result for PST 2:00 AM on 2011-11-06 is wrong.
Doing the same conversion using localtime() is correct.
During the ambiguous localtime hour on 6-Nov, 2:00 AM should only appear once. 1:00 AM should appear twice.

>>> from win32timezone import TimeZoneInfo
>>> from datetime import datetime
>>> import calendar
>>> import time
>>>
>>> tzi = TimeZoneInfo('Pacific Standard Time')
>>> tzutc = TimeZoneInfo('Coordinated Universal Time')
>>>
>>> def fromtimestamp_to_timetuple(timestamp):
...     tm = time.gmtime(timestamp)
...     tz1 = datetime(tm.tm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour,
...     tm.tm_min, tm.tm_sec, tzinfo=tzutc)
...     tz_time = tz1.astimezone(tzi)
...     return tz_time
...
>>> print fromtimestamp_to_timetuple(1320573600).timetuple()
time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=2, tm_min=0, tm_sec=0, tm_wday=6, tm_yday=310, tm_isdst=0)
>>> print fromtimestamp_to_timetuple(1320570000).timetuple()
time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=2, tm_min=0, tm_sec=0, tm_wday=6, tm_yday=310, tm_isdst=0)
>>> print fromtimestamp_to_timetuple(1320566400).timetuple()
time.struct_time(tm_year=2011, tm_mon=11, tm_mday=6, tm_hour=1, tm_min=0, tm_sec=0, tm_wday=6, tm_yday=310, tm_isdst=1)
>>>
>>> print time.strftime('%c', time.localtime(1320573600))
11/06/11 02:00:00
>>> print time.strftime('%c', time.localtime(1320570000))
11/06/11 01:00:00
>>> print time.strftime('%c', time.localtime(1320566400))
11/06/11 01:00:00


----------------------------------------------------------------------

>Comment By: Brian Matthews (bmatthews27)
Date: 2012-05-08 09:46

Message:
NOTE: This is a problem only at precisely the end of the hour. It is using
the most recent patches.

----------------------------------------------------------------------

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