bpo-46228: argparse docs: prog default is the basename of argv[0]

[lf-]

See the following snippet from the argparse source, which contradicts the current docs:

cpython/Lib/argparse.py

Lines 1733 to 1735 in e800dd1

	# default setting for prog
	if prog is None:
	prog = _os.path.basename(_sys.argv[0])

https://bugs.python.org/issue46228

[merwok]

Can you open a bug report on bugs.python.org?
See https://devguide.python.org/pullrequest/ for guidance

[lf-]

Can you open a bug report on bugs.python.org? See https://devguide.python.org/pullrequest/ for guidance

Done. See https://bugs.python.org/issue46228

[miss-islington]

Thanks @lf- for the PR, and @rhettinger for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[bedevere-bot]

GH-30339 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 74af713.

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/203) and take a look at the build logs.
4. Check if the failure is related to this commit (74af713) 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/203

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

== Tests result: ENV CHANGED ==

407 tests OK.

10 slowest tests:

• test_concurrent_futures: 3 min 32 sec
• test_multiprocessing_spawn: 2 min 31 sec
• test_multiprocessing_forkserver: 1 min 48 sec
• test_unparse: 1 min 33 sec
• test_asyncio: 1 min 18 sec
• test_tokenize: 1 min 15 sec
• test_lib2to3: 1 min
• test_logging: 58.5 sec
• test_capi: 56.8 sec
• test_ssl: 47.1 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: 8 min 57 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_d2f567b3'


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/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/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
KeyError: '/psm_5159c1f2'