rm: --preserve-root bypassed via a symlink to / (string check instead of dev/inode)

The --preserve-root check uses a path-string test path.hasroot && path.parent.isnone rather than comparing device/inode. A symlink to / e.g. /tmp/rootlink - / has a parent component, so it passes the check. GNU caches /'s dev/inode at startup and compares every traversed directory against it...