$('#myform :file[value!=\\'\\']') works in 1.2.6; not in 1.3.x

Selector is looking for inputs of type file with value not empty.

Test case where "uncaught exception: Syntax error, unrecognized expression: value!='']":

<div id="myform">

<form action="test-selector.php" enctype="multipart/form-data" method="post">

<div>

<input type="file" name="file" /><br />

<input type="file" name="file" /><br />

<input type="file" name="file" /><br />

<input type="button" value="Send" onclick="submit_form();" />

</div>

</form>

</div>

<!--

<script type="text/javascript" src="js/jquery-1.2.6.js"></script>

-->

<script type="text/javascript" src="js/jquery-1.3.1.js"></script>

<script type="text/javascript">

<![CDATA[

function submit_form(){

var files=$('#myform :file[value!=\\'\\']');

if(files.length>0){

files.each(

function(i){

console.log(this);

}

)

}

else{

alert('Select some files please');

}

}

]]>

</script>

Why doesn't value expression not work in the current release?