There seems to be a problem with multiFilter when filtering with descendant selectors. There may be other selectors that cause this problem as well, but I have only noticed it with descendant (space) and child (>) selectors.

The following code will return a jQuery object with the body element (expected: empty jQuery object):

$('body').filter('html>head');
// or
$('body').filter('html head');

Similarly, the following will return true (expected: false):

$('body').is('html>head');