gh-136264: Fix ``--relative-paths`` for PEP 739's build-details.json (#138510)

* KeyError is not raised for defaultdict
* Fix relative paths on different drives on Windows
* Add a round-trip test

Co-authored-by: Itamar Oren <itamarost@gmail.com>

Adam Turner committed 7mo ago

057ee1741015067b46446e46eab467c1fa82610d

Parent: 6401823

Committed by GitHub <noreply@github.com> on 9/8/2025, 9:14:05 AM