[Bug 885163] [NEW] pytz dst() incorrectly handles Pacific/Apia day leap

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Andreas Hasenack (ahasenack):

Request for SRU for Lucid, Maverick, Natty and Oneiric
======================================================

1. Impact
- Incorrect calculation of DST changes
- Landscape failure to accept new users or edit current users' setting
- "Django timezones app "timezones.zones" module unimportable" (reported on comment #11)

2. Development fix
The issue was fixed upstream in revision 268:
http://bazaar.launchpad.net/~stub/pytz/devel/revision/268

That is the diff grabbed for this SRU.

The same diff is also applied to the python-tz package in the current
ubuntu development version (precise).

3. Stable fix
The development fix applies cleanly to the stable releases.

4. Test case
Run the script below. If you get a backtrace, you are affected. If not, the bug is fixed in your environment:
#!/usr/bin/python
import pytz
from datetime import datetime
tz = pytz.timezone("Pacific/Apia")
d2 = datetime(2012,1,1)
local = tz.localize(d2)
local.dst()
print "All is good, NOT hit by bug #885163!"

5. Regression potential
Not sure, timezones can be tricky. I welcome comments from upstream for this section since I basically packaged their fix. The patch is minimal, and it fixed the problems we were having in our production servers.


Original bug description follows:
=================================
>>> from datetime import datetime
>>> import pytz
>>> tz = pytz.timezone('Pacific/Apia')
>>> d1 = datetime(2011, 11, 1)
>>> d2 = datetime(2012, 1, 1)
>>> tz.dst(d1)
datetime.timedelta(0, 3600)
>>> tz.dst(d2)
datetime.timedelta(1, 3600)

while utcoffset is correct:

>>> tz.utcoffset(d1)
datetime.timedelta(-1, 50400)
>>> tz.utcoffset(d2)
datetime.timedelta(0, 50400)

** Affects: pytz
     Importance: High
     Assignee: Stuart Bishop (stub)
         Status: Fix Released

** Affects: python-tz (Ubuntu)
     Importance: Undecided
         Status: Fix Released

** Affects: python-tz (Ubuntu Lucid)
     Importance: Undecided
         Status: New

** Affects: python-tz (Ubuntu Maverick)
     Importance: Undecided
         Status: New

** Affects: python-tz (Ubuntu Natty)
     Importance: Undecided
         Status: New

** Affects: python-tz (Ubuntu Oneiric)
     Importance: Undecided
         Status: New


** Tags: patch
-- 
pytz dst() incorrectly handles Pacific/Apia day leap
https://bugs.launchpad.net/bugs/885163
You received this bug notification because you are a member of Ubuntu Sponsors Team, which is subscribed to the bug report.