public static function tar_error_msg( $process_run ) {
		$stderr = trim( $process_run->stderr );
		$nl_pos = strpos( $stderr, "\n" );
		if ( false !== $nl_pos ) {
			$stderr = trim( substr( $stderr, 0, $nl_pos ) );
		}
		if ( $stderr ) {
			return sprintf( '%s (%d)', $stderr, $process_run->return_code );
		}
		return $process_run->return_code;
	}