function renameSync( oldPath, newPath ) {
	try {
		rename( oldPath, newPath );
	} catch ( err ) {
		return err;
	}
	return null;
}
Synchronously renames a file.

@param {(string|Buffer)} oldPath - old path
@param {(string|Buffer)} newPath - new path
@returns {(Error|null)} error object or null

@example
var err = renameSync( './beep/boop.txt', './beep/foo.txt' );
if ( err instanceof Error ) {
    throw err;
}