bpo-44734: Fix floating point precision in test_turtle

[befeleme]

Hello,
for context, we ran across the problematic test in Fedora, when older Pythons stopped building on 32-bit because of the strict assert. The patch made it build again. We haven't spotted the failure from Python 3.7 above.

The test failure is known: here and here. The changes in the turtle module code prevent the test from failing but it was pointed out that still the test is unnecessarily strict and it's better to have it relaxed.
The referred issue was already fixed for one of the two problematic asserts.

https://bugs.python.org/issue44734

[the-knights-who-say-ni]

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[miss-islington]

Thanks @befeleme for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.9, 3.10.
🐍🍒⛏🤖

[bedevere-bot]

GH-30960 is a backport of this pull request to the 3.10 branch.

[bedevere-bot]

GH-30961 is a backport of this pull request to the 3.9 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 macOS 3.x has failed when building commit aa78287.

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/725/builds/875) and take a look at the build logs.
4. Check if the failure is related to this commit (aa78287) 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/725/builds/875

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

== Tests result: ENV CHANGED ==

411 tests OK.

10 slowest tests:

• test_concurrent_futures: 3 min 42 sec
• test_multiprocessing_spawn: 2 min 26 sec
• test_multiprocessing_forkserver: 1 min 46 sec
• test_unparse: 1 min 21 sec
• test_asyncio: 1 min 16 sec
• test_tokenize: 1 min 13 sec
• test_logging: 1 min 3 sec
• test_lib2to3: 59.9 sec
• test_capi: 50.8 sec
• test_unicodedata: 46.8 sec

1 test altered the execution environment:
test_ftplib

17 tests skipped:
test_dbm_gnu 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 8 sec

Click to see traceback logs

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/threading.py", line 1031, in _bootstrap_inner
    self.run()
    ^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.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.x.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 214, in loop
    poll_fun(timeout, map)
    ^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 157, in poll
    read(obj)
    ^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 94, in read
    obj.handle_error()
    ^^^^^^^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/test/test_ftplib.py", line 421, in handle_error
    raise Exception
    ^^^^^^^^^^^^^^^
Exception
k


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
    ^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: '/psm_95befa41'


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/asyncore.py", line 90, in read
    obj.handle_read_event()
    ^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/buildbot/buildarea/3.x.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.x.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.x.pablogsal-macos-m1.macos-with-brew/build/Lib/ssl.py", line 1345, in do_handshake
    self._sslobj.do_handshake()
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
ssl.SSLZeroReturnError: TLS/SSL connection has been closed (EOF) (_ssl.c:998)


Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.x.pablogsal-macos-m1.macos-with-brew/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
    ^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: '/psm_e1e0a92c'

[encukou]

The buildbot failure in test_ftplib definitely looks unrelated. The next build (also of the main branch) succeeded.

test_ftplib seems a bit flaky on this buildbot: https://buildbot.python.org/all/#/builders/725