jquery autocomplete unbind bug

Shows bug when trying to unbind event handlers created as options in constructor.

HTML

<link rel="stylesheet" href="http://jqueryui.com/css/base.css">
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.7/themes/base/jquery-ui.css">
<input type="text" id="t1" />
<br />
<input type="text" id="t2" />

JavaScript

$(function() {
    //t1 doesn't work
    $('#t1').autocomplete({
        source: "aaa aab bbbb bbc cccc ccd dddd dde".split(' '),
        select: function(event, ui) {
            alert('selected: ' + ui.item.value);
        }
    });
    $('#t1').unbind("autocompleteselect");

    //t2 works
    $('#t2').autocomplete({
        source: "aaa aab bbbb bbc cccc ccd dddd dde".split(' ')
    });
    $('#t2').bind('autocompleteselect', function(event, ui) {
        alert('selected: ' + ui.item.value);
    });
    $('#t2').unbind("autocompleteselect");
});