[jQuery] jQuery.extend not working for function as target,is it a bug?

[Jacky]

/*
 * jQuery 1.2.1 - New Wave Javascript
 *
 * Copyright (c) 2007 John Resig (jquery.com)
 * Dual licensed under the MIT (MIT-LICENSE.txt)
 * and GPL (GPL-LICENSE.txt) licenses.
 *
 * $Date: 2007-11-29 07:53:54 +0800 (星期四, 29 十一月 2007) $
 * $Rev: 3973 $
 */

the jQuery reversion is #3973,function can't extend with
jQuery.extend.

function target(){
/**some code here*/
}

jQuery.extend(target,{
    someMethod:function(){
        /** some code here */
    }
});

alert(typeof target.someMethod);    // type of target.someMethod is
undefined