Description:
------------
If you create a form with a file input
and press submit without using the file input
it causes a notice, which it shouldnt do, and in 5.3 doesnt

Test script:
---------------
<?php
print_r($_POST);
print_r($_FILES);
?>
<form method="post" id="creation" enctype="multipart/form-data" action="" accept-charset="UTF-8">
        <label for="arttitle" id="labelarttitle">Title:</label>
        <input  type="text"  id="arttitle" name="arttitle" placeholder="Title" title="Title" />
        <input type="file" id="primaryImage" name="image1" placeholder="image1" title="Main Image" />
        <button type="submit" id="submitButtonID">Submit</button>
</form>

Expected result:
----------------
User created error, caused by user validation (if any)

not a PHP engine notice

Actual result:
--------------
PHP Engine notice