[3.14] gh-136264: Fix --relative-paths for PEP 739's build-details.json (GH-138510)

[miss-islington]

• KeyError is not raised for defaultdict
• Fix relative paths on different drives on Windows
• Add a round-trip test
  (cherry picked from commit 057ee17)

Co-authored-by: Adam Turner [email protected]
Co-authored-by: Itamar Oren [email protected]

• Issue: PEP-739 build-details generation is broken when --relative-paths is specified #136264

[hugovk]

Erm, let's have a passing CI before merge :)

test test_build_details crashed -- Traceback (most recent call last):
  File "/home/runner/work/cpython/cpython/Lib/test/libregrtest/single.py", line 210, in _runtest_env_changed_exc
    _load_run_test(result, runtests)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/runner/work/cpython/cpython/Lib/test/libregrtest/single.py", line 155, in _load_run_test
    test_mod = importlib.import_module(module_name)
  File "/home/runner/work/cpython/cpython/Lib/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1398, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1371, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1342, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 938, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 762, in exec_module
  File "<frozen importlib._bootstrap>", line 491, in _call_with_frames_removed
  File "/home/runner/work/cpython/cpython/Lib/test/test_build_details.py", line 182, in <module>
    @unittest.skipIf(is_wasm32, 'Feature not available on WebAssembly builds')
                     ^^^^^^^^^
NameError: name 'is_wasm32' is not defined. Did you mean: 'is_wasi'?

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[AA-Turner]

#138643 is a backport of is_wasm32 (#136815) to 3.14, which would be an alternative fix.

A

[AA-Turner]

Tests now passing

tests pass

[AA-Turner]

I didn't expect the Spanish Inquisition!

A

[AA-Turner]

Oh boo the fun trigger hasn't worked.

I have made the requested changes; please review again

[hugovk]

Thanks!