gh-115256: Remove refcycles from tarfile writing

[pan324]

• Issue: Remove reference cycle when writing tarfiles #115256

[AlexWaygood]

Not the biggest issue in the world, but it's a shame the PR title wasn't changed here before it was merged. The title of the resulting commit is pretty inaccurate :(

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Debian root 3.x has failed when building commit 0dfa7ce.

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/345/builds/7318) and take a look at the build logs.
4. Check if the failure is related to this commit (0dfa7ce) 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/345/builds/7318

Failed tests:

• test_bytes
• test_difflib
• test_tokenize
• test_io
• test_statistics
• test_pickle

Failed subtests:

• test_threads - test.test_io.CBufferedReaderTest.test_threads
• test_dict_chunking - test.test_pickle.CPicklerTests.test_dict_chunking
• test_recursion_limit - test.test_difflib.TestSFpatches.test_recursion_limit
• test_threads - test.test_io.PyBufferedRandomTest.test_threads
• test_inv_cdf - test.test_statistics.TestNormalDistPython.test_inv_cdf
• test_random_files - test.test_tokenize.TestRoundtrip.test_random_files

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_tokenize.py", line 1959, in test_random_files
    self.check_roundtrip(f)
    ~~~~~~~~~~~~~~~~~~~~^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_tokenize.py", line 1825, in check_roundtrip
    bytes_from5 = tokenize.untokenize(tokens5)
                  ~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/tokenize.py", line 333, in untokenize
    out = ut.untokenize(iterable)
          ~~~~~~~~~~~~~^^^^^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/tokenize.py", line 249, in untokenize
    self.add_whitespace(start)
    ~~~~~~~~~~~~~~~~~~~^^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/tokenize.py", line 176, in add_whitespace
    if row < self.prev_row or row == self.prev_row and col < self.prev_col:
                                                       ^^^^^^^^^^^^^^^^^^^
TypeError: '<' not supported between instances of 'Untokenizer' and 'int'


Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_statistics.py", line 2951, in test_inv_cdf
    self.assertAlmostEqual(iq.cdf(iq.inv_cdf(p)), p)
                                  ~~~~~~~~~~^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/statistics.py", line 1496, in inv_cdf
    if p <= 0.0 or p >= 1.0:
       ^^^^^^^^
TypeError: '<=' not supported between instances of 'NormalDist' and 'float'


Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_io.py", line 2430, in test_threads
    BufferedReaderTest.test_threads(self)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_io.py", line 1574, in test_threads
    random.shuffle(l)
    ~~~~~~~~~~~~~~^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/random.py", line 361, in shuffle
    x[i], x[j] = x[j], x[i]
                 ~^^^
TypeError: list indices must be integers or slices, not Random


Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_difflib.py", line 252, in test_recursion_limit
    difflib.SequenceMatcher(None, old, new).get_opcodes()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/difflib.py", line 525, in get_opcodes
    for ai, bj, size in self.get_matching_blocks():
                        ~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/difflib.py", line 454, in get_matching_blocks
    i, j, k = x = self.find_longest_match(alo, ahi, blo, bhi)
                  ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/difflib.py", line 386, in find_longest_match
    if k > bestsize:
       ^^^^^^^^^^^^
TypeError: '>' not supported between instances of 'SequenceMatcher' and 'int'


Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/pickletester.py", line 2279, in test_dict_chunking
    num_setitems = count_opcode(pickle.SETITEMS, s)
                   ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/pickletester.py", line 68, in count_opcode
    for op, dummy, dummy in pickletools.genops(pickle):
        if op.code == code.decode("latin-1"):
            n += 1
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/pickletools.py", line 2279, in _genops
    code = data.read(1)
           ~~~~~~~~~^^^
TypeError: '_io.BytesIO' object is not callable


Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_io.py", line 1574, in test_threads
    random.shuffle(l)
    ~~~~~~~~~~~~~~^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/random.py", line 361, in shuffle
    x[i], x[j] = x[j], x[i]
    ~^^^
TypeError: 'Random' object does not support item assignment


Traceback (most recent call last):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/string_tests.py", line 347, in test_find_periodic_pattern
    check_pattern(rr)
    ~~~~~~~~~~~~~^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/string_tests.py", line 339, in check_pattern
    right = ''.join(choices('abcdef', k=rr(2000)))
                    ~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/random.py", line 471, in choices
    return [population[floor(random() * n)] for i in _repeat(None, k)]
                             ~~~~~~^^
TypeError: 'Random' object is not callable

[encukou]

That failure looks quite unrelated.