yui io-upload-iframe suddenly stop working

Question

problem:　on ff the form submits to the original window which causes a refresh. on ie and chrome works fine but after the upload somehow the form's target attribute was set to "_blank"

the form just won't submit to the iframe transport, i checked the target attribute and everything and all goes find, even rollback to the previous working version. it just won't work anymore, help please. thanks

    Y.on('change', function(e) {
        if(!currentModule || !currentSelectedNode) return false;
         Y.once('io:start', uploadStart);
         Y.once('io:complete', uploadComplete);
         var cfg = {method : 'POST', form : { id : 'theme_form', upload : true }, data : 'doid=upload'};
         var url = CURRENT_URL  + '/';
         Y.io(url, cfg);
    }, '#image_upload');