gh-123780: Make test_pkgutil clean up spam module

[mhsmith]

When running the tests with --randomize, as is done by the buildbots, I came across this failure:

======================================================================
ERROR: test_find_class (test.test_pickle.CUnpicklerTests.test_find_class)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/msmith/git/python/cpython/Lib/test/pickletester.py", line 1265, in test_find_class
    self.assertRaises(ModuleNotFoundError, unpickler.find_class, 'spam', 'log')
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/msmith/git/python/cpython/Lib/unittest/case.py", line 804, in assertRaises
    return context.handle('assertRaises', args, kwargs)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/msmith/git/python/cpython/Lib/unittest/case.py", line 238, in handle
    callable_obj(*args, **kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
AttributeError: module 'spam' has no attribute 'log'

======================================================================
ERROR: test_find_class (test.test_pickle.PyUnpicklerTests.test_find_class)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/msmith/git/python/cpython/Lib/test/pickletester.py", line 1265, in test_find_class
    self.assertRaises(ModuleNotFoundError, unpickler.find_class, 'spam', 'log')
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/msmith/git/python/cpython/Lib/unittest/case.py", line 804, in assertRaises
    return context.handle('assertRaises', args, kwargs)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/msmith/git/python/cpython/Lib/unittest/case.py", line 238, in handle
    callable_obj(*args, **kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/Users/msmith/git/python/cpython/Lib/pickle.py", line 1620, in find_class
    return getattr(sys.modules[module], name)
AttributeError: module 'spam' has no attribute 'log'

----------------------------------------------------------------------
Ran 857 tests in 2.954s

FAILED (errors=2, skipped=31)
test test_pickle failed

This can be reproduced by running only test_pkgutil and test_pickle, in that order. test_pkgutil leaves behind a spam module in sys.modules, while test_pickle assumes there is no such module.

• Issue: test_pkgutil should clean up spam module #123780

[encukou]

PRs that need backporting should not skip issue; the issue number helps keep related PRs grouped together.

[miss-islington-app]

Thanks @mhsmith for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13.
🐍🍒⛏🤖

[bedevere-app]

GH-123781 is a backport of this pull request to the 3.13 branch.

[bedevere-app]

GH-123782 is a backport of this pull request to the 3.12 branch.

[mhsmith]

PRs that need backporting should not skip issue; the issue number helps keep related PRs grouped together.

OK, I'll remember that. But doesn't the original PR provide enough grouping already? It links to the backports, and the backports link to it.

[encukou]

Well, not as clearly as the issue's Linked PRs section :)