Last year, after many years of peacefully living the whole year in GMT-3, our government decided that Argentina should use DST again. This was done in a rush, but patches were written and applied everywhere to have a correct timezone.
Fixing the problem was not enough, tzdata's upstream decided to predict the future:
# From Paul Eggert (2007-12-22): # For dates after mid-2008, the following rules are my guesses and # are quite possibly wrong, but are more likely than no DST at all. Rule Arg 2007 only - Dec 30 0:00 1:00 S Rule Arg 2008 max - Mar Sun>=15 0:00 0 - Rule Arg 2008 max - Oct Sun>=1 0:00 1:00 S
Well, back in December 2007, October 2008 might have seemed like a long time in the future, and they assumed that sometime in the middle the correct date would be announced... But, predictably (knowing Argentina's current government), no DST has yet been announced.
However, Paul Eggert's guesses had propagated to almost all UNIX distributions, so that at 0:00 Sunday Oct 5th, all our computers were suddenly one hour ahead of time.
Affected systems: Debian, Ubuntu, Gentoo, Red Hat, OpenBSD, FreeBSD, Mac OS. Devices: ipod, maemo, Nokia N95. Websites: Clarin (a major newspaper - still broken 36 hours later), Gmail. And probably many others that I don't know of.
I even read that Windows was affected, although I don't know how that might be possible, since as far as I know they don't use tzdata.
Anyway, not satisfied with how they mistakenly predicted the future before, a few weeks ago (not enough time in advance to fix almost any systems, only sid had this release), they added this change:
# From Alexander Krivenyshev (2008-09-05): # As per message from Carlos Alberto Fonseca Arauz (Nicaragua), # Argentina will start DST on Sunday October 19, 2008. # # http://www.worldtimezone.com/dst_news/dst_news_argentina03.html # http://www.impulsobaires.com.ar/nota.php?id=57832 (in spanish) Rule Arg 2007 only - Dec 30 0:00 1:00 S Rule Arg 2008 max - Mar Sun>=15 0:00 0 - Rule Arg 2008 max - Oct Sun>=15 0:00 1:00 S
So, they decided to take the word of a guy from Nicaragua (no bad feelings against Nicaragua, but I think that this kind of stuff should be informed by people from the affected country), and from a couple of articles that say that "According to some sources, we might have to change our clocks on the third Sunday of October". Would you change tzdata sources with such information? I definitely wouldn't.
Anyway, Aurelien Jarno has already uploaded fixed packages, with no assumption regarding when the DST will happen, which is the sensible thing to do in a case like this. Thanks Aurel!