bpo-44257: fix "assigment_expr" typo + regenerate the grammar

[wimglenn]

Fixed typo and removed some unused imports - manual changes in python.gram & python_generator.py. Ran make regen-pegen and make regen-pegen-metaparser for the changes in generated files (parser.c & grammar_parser.py).

@pablogsal

https://bugs.python.org/issue44257

Automerge-Triggered-By: GH:pablogsal

[pablogsal]

Thanks for the PR, @wimglenn

[miss-islington]

Thanks @wimglenn for the PR, and @pablogsal for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖

[miss-islington]

Sorry, @wimglenn and @pablogsal, I could not cleanly backport this to 3.10 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 762173c6709f5cf3b59cbbe47d4e6fafbfe7ec2a 3.10

[bedevere-bot]

GH-29395 is a backport of this pull request to the 3.10 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 macOS 3.10 has failed when building commit 0e34a59.

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/724/builds/113) and take a look at the build logs.
4. Check if the failure is related to this commit (0e34a59) 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/724/builds/113

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

== Tests result: ENV CHANGED ==

407 tests OK.

10 slowest tests:

• test_concurrent_futures: 3 min 35 sec
• test_multiprocessing_spawn: 2 min 28 sec
• test_multiprocessing_forkserver: 1 min 48 sec
• test_unparse: 1 min 34 sec
• test_asyncio: 1 min 19 sec
• test_tokenize: 1 min 12 sec
• test_lib2to3: 1 min 2 sec
• test_logging: 58.1 sec
• test_capi: 58.0 sec
• test_io: 46.8 sec

1 test altered the execution environment:
test_ftplib

16 tests skipped:
test_devpoll test_epoll test_gdb test_ioctl test_msilib
test_multiprocessing_fork test_ossaudiodev test_spwd
test_startfile test_tix test_tk test_ttk_guionly test_winconsoleio
test_winreg test_winsound test_zipfile64

Total duration: 9 min 24 sec

Click to see traceback logs

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_05b7611f'


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/threading.py", line 1009, in _bootstrap_inner
    self.run()
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_ftplib.py", line 298, in run
    asyncore.loop(timeout=0.1, count=1)
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 214, in loop
    poll_fun(timeout, map)
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 157, in poll
    read(obj)
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 94, in read
    obj.handle_error()
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_ftplib.py", line 421, in handle_error
    raise Exception
Exception


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 90, in read
    obj.handle_read_event()
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_ftplib.py", line 384, in handle_read_event
    self._do_ssl_handshake()
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_ftplib.py", line 345, in _do_ssl_handshake
    self.socket.do_handshake()
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/ssl.py", line 1341, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLZeroReturnError: TLS/SSL connection has been closed (EOF) (_ssl.c:997)


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.10.pablogsal-macos-m1.macos-with-brew/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_58fd413c'

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Debian root 3.10 has failed when building commit 0e34a59.

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/664/builds/502) and take a look at the build logs.
4. Check if the failure is related to this commit (0e34a59) 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/664/builds/502

Failed tests:

• test_signal

Failed subtests:

• test_stress_modifying_handlers - test.test_signal.StressTest

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

== Tests result: FAILURE then FAILURE ==

407 tests OK.

10 slowest tests:

• test_shelve: 3 min 38 sec
• test_concurrent_futures: 3 min 12 sec
• test_multiprocessing_spawn: 2 min 20 sec
• test_multiprocessing_forkserver: 1 min 36 sec
• test_mailbox: 1 min 32 sec
• test_unparse: 1 min 23 sec
• test_tokenize: 1 min 18 sec
• test_peg_generator: 1 min 17 sec
• test_capi: 1 min 16 sec
• test_multiprocessing_fork: 1 min 16 sec

1 test failed:
test_signal

19 tests skipped:
test_devpoll test_gdb test_idle test_ioctl test_kqueue test_msilib
test_smtpnet test_ssl test_startfile test_tcl test_tix test_tk
test_ttk_guionly test_ttk_textonly test_turtle test_winconsoleio
test_winreg test_winsound test_zipfile64

1 re-run test:
test_signal

Total duration: 21 min 15 sec

Click to see traceback logs

Traceback (most recent call last):
  File "/root/buildarea/3.10.angelico-debian-amd64/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_eb4af476'


Traceback (most recent call last):
  File "/root/buildarea/3.10.angelico-debian-amd64/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_ab026948'


Traceback (most recent call last):
  File "/root/buildarea/3.10.angelico-debian-amd64/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_6ed799ec'


Traceback (most recent call last):
  File "/root/buildarea/3.10.angelico-debian-amd64/build/Lib/test/test_signal.py", line 1307, in test_stress_modifying_handlers
    self.assertGreater(num_received_signals, 0)
AssertionError: 0 not greater than 0