[tz] [PATCH] Updates for Chile 2013

[Robert Elz]

    Date:        Wed, 20 Feb 2013 22:55:04 +0100
    From:        Petr Machata <pmachata at redhat.com>
    Message-ID:  <m2ehgaljwl.fsf at redhat.com>

  | I decided to apply the transition dates to single years only--the DST
  | policy is reevaluated every year anyway.

I think that's a mistake - you're guaranteeing that the data is going
to be wrong, rather than simply making it likely.

I'd suggest that the data be changed as ...

--- southamerica.was	2012-07-25 21:13:46.000000000 +0700
+++ southamerica	2013-02-21 07:37:16.000000000 +0700
@@ -1277,10 +1277,8 @@
 Rule	Chile	2010	only	-	Apr	Sun>=1	3:00u	0	-
 Rule	Chile	2011	only	-	May	Sun>=2	3:00u	0	-
 Rule	Chile	2011	only	-	Aug	Sun>=16	4:00u	1:00	S
-Rule	Chile	2012	only	-	Apr	Sun>=23	3:00u	0	-
-Rule	Chile	2012	only	-	Sep	Sun>=2	4:00u	1:00	S
-Rule	Chile	2013	max	-	Mar	Sun>=9	3:00u	0	-
-Rule	Chile	2013	max	-	Oct	Sun>=9	4:00u	1:00	S
+Rule	Chile	2012	max	-	Apr	Sun>=23	3:00u	0	-
+Rule	Chile	2012	max	-	Sep	Sun>=2	4:00u	1:00	S
 # IATA SSIM anomalies: (1992-02) says 1992-03-14;
 # (1996-09) says 1998-03-08.  Ignore these.
 # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]

That is, it turns out that the rules we inserted for 2012 apply for 2013
as well (except we were conservative last year, and assumed the change then
was just a one year thing, and put the older dates back for 2013).

So, the patch above just assumes that the 2012/2013 strategy will continue
forwards, which it might ... it is also possible that it won't, and we will
need to change it again next year (or even again later this year) but
some kind of reasonable guess is better than simply assuming that summer time
is going to start next September, and then never end.

kre