Description:
------------
The virtual() function works great, but not headers_sent()!

headers_sent() returns true with an empty string as filename & indicates that the line number is zero!

Reproduce code:
---------------
<?php
virtual("empty.php");	// An empty file
var_dump(headers_sent($file, $line), $file, $line);
?>

Expected result:
----------------
bool(false)
string(0) ""
int(0)


Actual result:
--------------
bool(true)
string(0) ""
int(0)