DST law changes in Greenland and Mexico.  Notably, a new timezone
America/Ciudad_Juarez has been split off from America/Ojinaga.

Historical corrections for northern Canada, Colombia, and Singapore.

DST law changes in Chile, Fiji, Iran, Jordan, Mexico, Palestine,
and Syria.  Historical corrections for Chile, Crimea, Iran, and
Mexico.

Also, the Europe/Kiev zone has been renamed to Europe/Kyiv
(retaining the old name as a link).

The following zones have been merged into nearby, more-populous zones
whose clocks have agreed since 1970: Antarctica/Vostok, Asia/Brunei,
Asia/Kuala_Lumpur, Atlantic/Reykjavik, Europe/Amsterdam,
Europe/Copenhagen, Europe/Luxembourg, Europe/Monaco, Europe/Oslo,
Europe/Stockholm, Indian/Christmas, Indian/Cocos, Indian/Kerguelen,
Indian/Mahe, Indian/Reunion, Pacific/Chuuk, Pacific/Funafuti,
Pacific/Majuro, Pacific/Pohnpei, Pacific/Wake and Pacific/Wallis.
(This indirectly affects zones that were already links to one of
these: Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland,
Pacific/Ponape, Pacific/Truk, and Pacific/Yap.)  America/Nipigon,
America/Rainy_River, America/Thunder_Bay, Europe/Uzhgorod, and
Europe/Zaporozhye were also merged into nearby zones after discovering
that their claimed post-1970 differences from those zones seem to have
been errors.

While the IANA crew have been working on merging zones that have no
post-1970 differences for some time, this batch of changes affects
some zones that are significantly more populous than those merged
in the past, notably parts of Europe.  The loss of pre-1970 timezone
history for those zones may be troublesome for applications
expecting consistency of timestamptz display.  As an example, the
stored value '1944-06-01 12:00 UTC' would previously display as
'1944-06-01 13:00:00+01' if the Europe/Stockholm zone is selected,
but now it will read out as '1944-06-01 14:00:00+02'.

There exists a "packrat" option that will build the timezone data
files with this old data preserved, but the problem is that it also
resurrects a bunch of other, far less well-attested data; so much so
that actually more zones' contents change from 2022a with that option
than without it.  I have chosen not to do that here, for that reason
and because it appears that no major OS distributions are using the
"packrat" option, so that doing so would cause Postgres' behavior
to diverge significantly depending on whether it was built with
--with-system-tzdata.  However, for anyone for whom these changes pose
significant problems, there is a solution: build a set of timezone
files with the "packrat" option and use those with Postgres.

DST law changes in Palestine.  Historical corrections for
Chile and Ukraine.

DST law changes in Fiji, Jordan, Palestine, and Samoa.  Historical
corrections for Barbados, Cook Islands, Guyana, Niue, Portugal, and
Tonga.

Also, the Pacific/Enderbury zone has been renamed to Pacific/Kanton.
The following zones have been merged into nearby, more-populous zones
whose clocks have agreed since 1970: Africa/Accra, America/Atikokan,
America/Blanc-Sablon, America/Creston, America/Curacao,
America/Nassau, America/Port_of_Spain, Antarctica/DumontDUrville,
and Antarctica/Syowa.

DST law changes in Russia (Volgograd zone) and South Sudan.
Historical corrections for Australia, Bahamas, Belize, Bermuda,
Ghana, Israel, Kenya, Nigeria, Palestine, Seychelles, and Vanuatu.
Notably, the Australia/Currie zone has been corrected to the point
where it is identical to Australia/Hobart.

DST law changes in Palestine, with a whopping 120 hours' notice.
Also some historical corrections for Palestine.

DST law changes in Morocco, Canadian Yukon, Fiji, Macquarie Island,
Casey Station (Antarctica).  Historical corrections for France,
Hungary, Monaco.

DST law changes in Morocco and the Canadian Yukon.
Historical corrections for Shanghai.

The America/Godthab zone is renamed to America/Nuuk to reflect
current English usage; however, the old name remains available as a
compatibility link.

DST law changes in Fiji and Norfolk Island.  Historical corrections
for Alberta, Austria, Belgium, British Columbia, Cambodia, Hong Kong,
Indiana (Perry County), Kaliningrad, Kentucky, Michigan, Norfolk
Island, South Korea, and Turkey.

Brazil no longer observes DST.
Historical corrections for Palestine, Hong Kong, and Italy.

DST law changes in Palestine and Metlakatla.
Historical corrections for Israel.

Etc/UCT is now a backward-compatibility link to Etc/UTC, instead
of being a separate zone that generates the abbreviation "UCT",
which nowadays is typically a typo.  Postgres will still accept
"UCT" as an input zone name, but it won't output it.

DST law changes in Kazakhstan, Metlakatla, and São Tomé and Príncipe.
Kazakhstan's Qyzylorda zone is split in two, creating a new zone
Asia/Qostanay, as some areas did not change UTC offset.
Historical corrections for Hong Kong and numerous Pacific islands.

DST law changes in Morocco (with, effectively, zero notice).
Historical corrections for Hawaii.

DST law changes in Chile, Fiji, and Russia (Volgograd).
Historical corrections for China, Japan, Macau, and North Korea.

Note: like the previous tzdata update, this involves a depressingly
large amount of semantically-meaningless churn in tzdata.zi.  That
is a consequence of upstream's data compression method assigning
unstable abbreviations to DST rulesets.  I complained about that
to them last time, and this version now uses an assignment method
that pays some heed to not changing abbreviations unnecessarily.
So hopefully, that'll be better going forward.

DST law changes in North Korea.  Redefinition of "daylight savings" in
Ireland, as well as for some past years in Namibia and Czechoslovakia.
Additional historical corrections for Czechoslovakia.

With this change, the IANA database models Irish timekeeping as following
"standard time" in summer, and "daylight savings" in winter, so that the
daylight savings offset is one hour behind standard time not one hour
ahead.  This does not change their UTC offset (+1:00 in summer, 0:00 in
winter) nor their timezone abbreviations (IST in summer, GMT in winter),
though now "IST" is more correctly read as "Irish Standard Time" not "Irish
Summer Time".  However, the "is_dst" column in the pg_timezone_names view
will now be true in winter and false in summer for the Europe/Dublin zone.

Similar changes were made for Namibia between 1994 and 2017, and for
Czechoslovakia between 1946 and 1947.

So far as I can find, no Postgres internal logic cares about which way
tm_isdst is reported; in particular, since commit b2cbced we do not
rely on it to decide how to interpret ambiguous timestamps during DST
transitions.  So I don't think this change will affect any Postgres
behavior other than the timezone-view outputs.

Discussion: https://postgr.es/m/30996.1525445902@sss.pgh.pa.us

DST law changes in Palestine and Antarctica (Casey Station).  Historical
corrections for Portugal and its colonies, as well as Enderbury, Jamaica,
Turks & Caicos Islands, and Uruguay.

DST law changes in Brazil, Sao Tome and Principe.  Historical corrections
for Bolivia, Japan, and South Sudan.  The "US/Pacific-New" zone has been
removed (it was only a link to America/Los_Angeles anyway).

Traditionally IANA has distributed their timezone data in pure source
form, replete with extensive historical comments.  As of release 2017c,
they've added a compact single-file format that omits comments and
abbreviates command keywords.  This form is way shorter than the pure
source, even before considering its allegedly better compressibility.
Hence, let's distribute the data in that form rather than pure source.

I'm pushing this now, rather than at the next timezone database update,
so that it's easy to confirm that this data file produces compiled zic
output that's identical to what we were getting before.

Discussion: https://postgr.es/m/1915.1511210334@sss.pgh.pa.us