extending Debug::vars(), see http://forum.kohanaframework.org/discussion/comment/59485#Comment_59485

debug.php

class Debug extends Kohana_Debug {

	public static function vars()
	{
		if (func_num_args() === 0)
			return;

		$backtrace = debug_backtrace();
		$path = $backtrace[0]['file'];
		$filename = Debug::path($path);
		$line = $backtrace[0]['line'];
		$header = '<b>'.$filename.':'.$line.'</b>';
		$body = call_user_func_array('Kohana_Debug::vars', func_get_args());

		return $header.$body;
	}
}