bpo-45162: Revert "Remove many old deprecated unittest features"

[gpshead]

This reverts commit b0a6ede.

We're deferring this change until 3.12 while upstream projects that use
the legacy assertion method names are fixed. See the issue for links
to the discussion.

https://bugs.python.org/issue45162

[vstinner]

I don't understand the Docs CI failure:

PATH=./venv/bin:$PATH sphinx-build -b doctest -d build/doctrees -q -W --keep-going -j4 -W . build/doctest ...
make[1]: *** [Makefile:51: build] Error 1
make[1]: Leaving directory '/home/runner/work/cpython/cpython/Doc'
Testing of doctests in the sources finished, look at the results in build/doctest/output.txt
make: *** [Makefile:131: doctest] Error 1
make: Leaving directory '/home/runner/work/cpython/cpython/Doc'
Error: Process completed with exit code 2.

[vstinner]

Ah, maybe the warning is treated as an error:

Warning: ../build/NEWS:83: WARNING: Unknown interpreted text role "module".

[vstinner]

I guess that the change is related to this python-dev discussion:
https://mail.python.org/archives/list/python-dev@python.org/thread/GJTREADEXYAETECE5JDTPYWK4WMTKYGR/

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 C9S 3.x has failed when building commit b50322d.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/791/builds/4) and take a look at the build logs.
4. Check if the failure is related to this commit (b50322d) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/791/builds/4

Summary of the results of the build (if available):

Click to see traceback logs

remote: Enumerating objects: 21, done. remote: Counting objects: 4% (1/21) remote: Counting objects: 9% (2/21) remote: Counting objects: 14% (3/21) remote: Counting objects: 19% (4/21) remote: Counting objects: 23% (5/21) remote: Counting objects: 28% (6/21) remote: Counting objects: 33% (7/21) remote: Counting objects: 38% (8/21) remote: Counting objects: 42% (9/21) remote: Counting objects: 47% (10/21) remote: Counting objects: 52% (11/21) remote: Counting objects: 57% (12/21) remote: Counting objects: 61% (13/21) remote: Counting objects: 66% (14/21) remote: Counting objects: 71% (15/21) remote: Counting objects: 76% (16/21) remote: Counting objects: 80% (17/21) remote: Counting objects: 85% (18/21) remote: Counting objects: 90% (19/21) remote: Counting objects: 95% (20/21) remote: Counting objects: 100% (21/21) remote: Counting objects: 100% (21/21), done. remote: Compressing objects: 10% (1/10) remote: Compressing objects: 20% (2/10) remote: Compressing objects: 30% (3/10) remote: Compressing objects: 40% (4/10) remote: Compressing objects: 50% (5/10) remote: Compressing objects: 60% (6/10) remote: Compressing objects: 70% (7/10) remote: Compressing objects: 80% (8/10) remote: Compressing objects: 90% (9/10) remote: Compressing objects: 100% (10/10) remote: Compressing objects: 100% (10/10), done. remote: Total 21 (delta 11), reused 11 (delta 11), pack-reused 0 
From https://github.com/python/cpython
* branch main -> FETCH_HEAD
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Turn off this advice by setting config variable advice.detachedHead to false
HEAD is now at b50322d203 [bpo-45162](https://bugs.python.org/issue45162): Revert "Remove many old deprecated unittest features" (GH-30935)
Switched to and reset branch 'main'
In file included from ../Modules/expat/xmltok.c:57:
../Modules/expat/xmltok_ns.c: In function ‘findEncoding’:
../Modules/expat/xmltok.h:276:10: warning: ‘buf’ may be used uninitialized [-Wmaybe-uninitialized]
276 | (((enc)->utf8Convert)(enc, fromP, fromLim, toP, toLim))
|~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../Modules/expat/xmltok.h:276:10: note: by argument 5 of type ‘const char *’ to ‘XML_Convert_Result <T6d3> (const struct ENCODING *, const char * *, const char *, char * *, const char *)’
In file included from ../Modules/expat/xmltok.c:1654:
../Modules/expat/xmltok_ns.c:96:8: note: ‘buf’ declared here
96 | char buf[ENCODING_MAX];
|^~~
In file included from ../Modules/expat/xmltok.c:57:
../Modules/expat/xmltok_ns.c: In function ‘findEncodingNS’:
../Modules/expat/xmltok.h:276:10: warning: ‘buf’ may be used uninitialized [-Wmaybe-uninitialized]
276 | (((enc)->utf8Convert)(enc, fromP, fromLim, toP, toLim))
|~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../Modules/expat/xmltok.h:276:10: note: by argument 5 of type ‘const char *’ to ‘XML_Convert_Result <T6d3> (const struct ENCODING *, const char * *, const char *, char * *, const char *)’
In file included from ../Modules/expat/xmltok.c:1665:
../Modules/expat/xmltok_ns.c:96:8: note: ‘buf’ declared here
96 | char buf[ENCODING_MAX];
|^~~lto1: fatal error: error writing to /tmp/ccY9JaSx.s: No space left on device
compilation terminated.
lto-wrapper: fatal error: gcc returned 1 exit status
compilation terminated.
/usr/bin/ld: error: lto-wrapper failedcollect2: error: ld returned 1 exit statusmake: *** [Makefile:1170: Programs/_freeze_module] Error 1find: ‘build’: No such file or directoryfind: ‘build’: No such file or directoryfind: ‘build’: No such file or directoryfind: ‘build’: No such file or directorymake: [Makefile:2464: clean-retain-profile] Error 1 (ignored)