uutils coreutils mv Silent Ownership Loss in Cross-Device Operations

The mv utility in uutils coreutils fails to preserve file ownership during moves across different filesystem boundaries. The utility falls back to a copy-and-delete routine that creates the destination file using the caller's UID/GID rather than the source's metadata. This flaw breaks backups and migrations, causing files moved by a privileged user (e.g., root) to become root-owned unexpectedly, which can lead to information disclosure or restricted access for the intended owners.