The pkgmgr proxy layer may intentionally terminate the process via SystemExit(0). The previous test logic interpreted any SystemExit as a failure, causing false negatives during `pkgmgr clone --all` E2E runs. This patch updates `test_clone_all.py` to: - accept SystemExit(0) as a successful run, - only fail on non-zero exit codes, - preserve diagnostic output for real failures. This stabilizes the clone-all E2E test across proxy-triggered exits. https://chatgpt.com/share/69393f6b-b854-800f-aabb-25811bbb8c74