Inconsistent POSIX TZ string returned by tzdump depending of time machine

[homer242]

Hello,

I found a problem with tzdump program. The TZ string returned by tzdump can be different depending if the machine time is in DST or not.

For instance, with America/Iqaluit timezone and tzdata-2021a, tzdump gives me for today, nov 9:

$ date
Wed 09 Nov 2022 10:49:45 AM CET
$ tzdump -q -p . America/Iqaluit
# America/Iqaluit
EST5EDT,M3.2.0,M11.1.0

But if I change my machine time to be 1 september (the point here is to switch to daylight saving time on the machine), tzdump gives me an another TZ POSIX string:

$ sudo date -s "1 SEP 2022 11:00:00"
$ date
Thu 01 Sep 2022 11:02:23 AM CEST
$ tzdump -q -p . America/Iqaluit
# America/Iqaluit
EST5EDT,M3.2.0/3,M11.1.0

Several timezones give different TZ strings depending of the machine time (Iqaluit, Troll, Gaza, Hebron, ...), not all timezones contained in the tz database.

[kurahaupo]

To be clear, the difference between those strings is the insertion of /3, which changes the time-of-day when DST starts, from 2am to 3am.

@homer242, could you please clarify which is the correct one for the Iqualuit timezone?