[jdotc1]

os.pathsep.join(str(i) for i in self._backend_paths).strip() removes a valid trailing space from the final backend directory. A backend located in a POSIX directory named 'backend ' cannot be imported by the real child process.

Remove only .strip() from the joined backend-path string. Add three real child-process backend tests for ordinary names, embedded spaces and a trailing space. No changelog fragment is added: current comparable merged PR #326 changes only implementation and tests, and no mandatory fragment rule was found.

Testing

118 tests passed; the configured 100% coverage gate passed (1,204 statements and 136 branches). Ruff check, Ruff format check and the declared ty 0.0.24 type checker passed. A clean applied checkout built a wheel and passed all 3 new cases. Full Python 3.12 suite and the 100% coverage gate passed. The repository-wide type check passed using ty 0.0.24 with its declared type/docs dependencies.

Removing strip preserves filesystem spelling; joining zero paths still returns an empty string. No shell is introduced and argv remains unchanged. Only the trailing-space filesystem case is skipped on Windows; ordinary and embedded-space cases remain portable.

Validation results above are from the reviewed patch on upstream commit d248e76ec2a23f8d13f1abc2e49e8c1d037c9a2d.

[jdotc1]

Could a maintainer approve the check workflow for the current head (21f3c64)? It is waiting for authorization before the checks can run. Thank you.