Preserve the original file when in-place CLI replacement fails

[xingzhao-ji]

The in-place CLI currently catches any error from creating a backup, copying permissions, or renaming the replacement, then unlinks the original and retries. A repeated rename failure leaves the original file missing. A failed backup or chmod can also be silently ignored.

Use os.replace to overwrite the destination on POSIX and Windows without unlinking it first. If a preparation or replacement step fails, keep the original, clean up the temporary file, and propagate the error. An existing .orig backup now causes the command to fail instead of silently modifying the original without the requested backup.

Regression coverage checks a persistent replacement error, a chmod error, and a pre-existing backup. All three fail against the original source and pass with this change. The existing input-handle regression now checks the replacement call.

Validation:

• python tests.py: 212 tests pass on Python 3.12.14 and 3.13.5.
• Ruff syntax/undefined-name checks and git diff --check pass.
• The separate Hypothesis property suite was not run because Hypothesis is unavailable in the test environment. Windows was not run locally.

[stefankoegl]

Looks good to me. @fhgffy you touched that part of the code recently. What do you think?

[coveralls]

coverage: 100.0%. remained the same — xingzhao-ji:fix-cli-preserve-original-on-replace-error into stefankoegl:master

[Copilot]

🟢 Approval recommended

The focused change removes the destructive fallback and includes regression coverage for the reported failure paths.

No open issues 🎉

What changed in this PR

This PR makes in-place CLI updates safer by preserving the original file when preparation or replacement fails.

Changes:

• Uses os.replace instead of deleting the original and retrying.
• Cleans up temporary files and propagates failures.
• Adds failure-path regressions and updates the input-handle check.

File	Description
tests.py	Tests original-file preservation, temporary-file cleanup, and input closure before replacement.
jsonpatch_cli.py	Removes the destructive fallback and uses os.replace.

_{Review effort: Balanced}