If the PYTZ_SKIPEXISTSCHECK environment variable is set, pytz
will not confirm the existance of the expected timezone database
files at import time. This improves startup time, but will cause
crashes when the timezone list baked into the pytz release does
not match the timezone database in use.

Patch from Timothy Paine

9c175ec6c Release 2020d
65f1deaca * tz-link.html: Fix typo
b80ed1696 Fix Palestine 2015 fall and 2020 spring
efd0231aa Palestine ends DST on 2020-10-24
103e7868c Fail on ZIC_BLOAT_DEFAULT typo
980306471 Improve TZUpdater and Python links
ce89cbaa4 Port ‘make rearguard_tarballs’ to macOS
43dda7dbe Cite Tom Scott on Danish time
40e0dc322 Update Danish URLs
ab21ad971 Release 2020c
dc43ed588 * europe (Hungary): Add more URLs (thanks to Géza Nyáry).
0c8cac40a Put dummy pacificnew into rearguard tarball
27264eae8 * ziguard.awk: Add limitations commentary.
6a244fd41 * europe: Hungary URL comments (thanks to Michael Deckers).
d5c1b97cd Fiji observes DST from 2020-12-20 to 2021-01-17
47311d42a Release 2020b
64308c005 * NEWS: Fix Antarctic seasons, Casey change is past
06520a2b4 Tighten up scope wording
c5f6ef851 Convert tz-how-to.html to HTML 5
110feebd9 Further update code to match Link line field names
284e877d7 Drop support for zic -y, Rule TYPEs, pacificnew
b3cf2ee42 Remove obsolete file systemv
d6abc89b3 * antarctica (Antarctica/Casey): Correct 2019-10 transition.
6427fe6c0 Fixes for Casey and Macquarie
dd606383a * NEWS: Fix typo (thanks to Philip Paeps).
d3bdef36c Yukon’s change is effective 2020-11-01.
afc53e03f * tz-link.html: Cite PyPI tzdata (thanks to Paul Ganssle).
2c431bd71 * tz-link.html: Cite Python 3.9 (thanks to Matt Johnson-Pint).
abbe4eeee * tz-art.html: Add Mr. Monk (thanks to Arthur David Olson).
241e6df07 Improve heads-up advice
cb2d288ae * tz-link.html: Cite TZDIST list.  (Thanks to Michael Douglass.)
d7451484e Cite Rishi et al in tz-link
3e865829e * asia: Cite Barak 2020 on Israeli DST controversy.
a9f132757 Mention Intl.DateTimeFormat
243321439 * README: Add a pointer to tz-how-to.html.
6d25c3e89 date: simplify format compuation
dca583ac6 date: redo strftime buffer-exhaustion check
8b238ec54 strftime: conform better to POSIX+
6e2e87703 Minor editorial improvements for newstrftime.3
ba912ae8b * backzone: More commentary re 1940s Bahrain.
39c661ee1 Update Bahrain as per article in The National
63699ef40 Fix leapseconds comment when EXPIRES_LINE
b04741d80 No leap second on 2020-12-31
efbae189b Cite Mirmalek on Martian timekeeping
6ba6f2117 zic now defaults to ‘-b slim’
08c326dfd Do not install 'posixrules' by default
180f76a2d zic has new ‘-l -’ and ‘-p -’ options
c9e377825 * europe: Fix minor comment typos in previous change.
ccbd7d2ef Go back to midnight transitions for France etc.
812249354 * NEWS: Fix recent date typo.
ddb5717c5 Further fixes to 1891 and 1911 French transitions
1c8ce71c3 French clocks stopped for 9′21″ on 1911-03-11
f8eca4dc2 * europe: Add Hungaricana URLs (thanks to Géza Nyáry).
1d8d276b3 Improve 1890 Hungarian transition.
f87ed56da Fix Hungarian transitions 1918-1983
e30fe68d4 Predict Morocco spring-forward after Eid al-Fitr
243ae0709 Fix comment typo re 1900 Spanish decree
c6c18a432 More Ruthenia replacement
b43b6b46b Mention TimeZoneDB’s CSV and SQL files.
402965e63 Use bold for command and func names in man pages
d36f8f5b6 Remove tzsetwall

git-subtree-dir: tz
git-subtree-split: d828740bbde9367c28fda3c08d26db59f0865162

pytz can still only read the deprecated 'fat' compiled timezone
datafiles.

Support for 'slim' datafiles should be done by using the
Python 3.9 parser and the available backports. Python 2.7
will be stuck only able to use the 'fat' format.

Addresses lp:1876176

Python 3.0 has been untested for a while, and I doubt it works.

efc5c0619 Release 2020e
b804a741d Improve doc of zic coalescing zone+DST transitions
c8891f390 Cite publication of Volgograd change
316c1598e Correct LMT and pre-1919 transitions for Nigeria
3dcdea78d Fix NEWS typo
c983a0fb7 Document zic coalescing zone+DST transitions
ce7b1bbc7 Seychelles switched from LMT to +04 on 1907-01-01
b980f1cac Model Turks & Caicos time 2015-2018 as AST
ff90fc93a Fix Vanuatu DST in 1973-1974 and 1984 transition
7c7419c6a Volgograd change likely December 27, not 20
0b5ae1fb7 Fix some errors in recent Bahamas changes
cd1769fe6 Fix Ghana again, for 1942 through 1946
3831c591e Fix Volgograd label in {zone,zone1970}.tab
adf4d8d35 Fix several pre-1946 transitions for Bahamas
0415d0e5f Re-fix Ghana typo for 1919/1920
6e7558f19 Fix Ghana typo for 1919/1920
271d9438b Volgograd switches from +04 to +03 on 12-20 02:00
a499dd6e0 * northamerica: Add URL for Yukon OIC 1980/02
7cc6d7c00 Fix several pre-1957 transitions for Ghana
17acee8cb Fix several pre-1957 transitions for Bermuda
1aca4cad3 Fix several pre-1972 transitions for Australia
a47ef9c71 * tz-link.html: Use <abbr> more systematically.
48e68fbfd Document "right" seconds better
beba17f43 Fix mistaken Belize interpretation
d7e93bdba Fix several Belize transitions 1942/1968
b231fbdb5 Port 'make rearguard_tarballs' to Solaris 10
8b21cc5d2 Fix Israel and Palestine transitions 1940/1985
52ba05422 Fix zone*.tab Yukon comment columns
b106a6e84 leapseconds now says why NIST, not IERS
eff0719a7 Fix Kenya transitions 1908/1960
78422f077 Use better fallback for unknown $(VERSION)
ac029805c * etcetera: Update comment in the light of Neil Fuller’s comments.
e4645c40a Port to downstream HP-UX-style ‘make’

git-subtree-dir: tz
git-subtree-split: a816a5c4de427cae12477455dea2bc4eb990b2c9

336c8f8262 Release 2021a
91edda4982 Update web links
7d7a4fb5bd South Sudan changes from +03 to +02 on 2021-02-01.
500141665b No leap second on 2021-06-30
846c3ac7ab Release 2020f
15e0ac32c1 Fix rearguard.zi corruption in 2020e

git-subtree-dir: tz
git-subtree-split: 4f0b29ebf7b3da8ab5f8415abb8f47162ef9502c