Description:
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Running IIS 6 on Windows 2003 server. 

After an update to the most recent version of php 5.1.2, for some reacon a function handling uploaded using is_file stopped working. is_file failed for existing files. I fixed it by changing is_file to file_exists, then it worked again. Prior to the update, in the older version, presumably it was 5.0.1, is_file worked just fine without problems.


Reproduce code:
---------------
<?php
echo 'is_file:' . (is_file($_FILES['myfile']['tmp_name']) ? 'true' : 'false');
echo 'file_exists:' . (file_exists($_FILES['myfile']['tmp_name']) ? 'true' : 'false');
 ?>
<form action="<?php echo $_SERVER['PHP_SELF'] ?>" enctype="multipart/form-data" method="post">
<input type="file" name="myfile" />
<input type="submit" />
</form>

Expected result:
----------------
is_file:truefile_exists:true

Actual result:
--------------
is_file:falsefile_exists:true