Description:
------------
I called extract($array, EXTR_SKIP) in the global scope on an array and one of the variables did not extract, even thought it was not set.

I traced the problem to a function call in which there was a global statement involving the variable.  This seems to have created the variable in the global scope, but isset($var) (in the global scope) and isset($GLOBALS["var"]) both return false.  So, the variable is not set, but it will not extract.  

The only way to detect that it is in the symbol table is to do a print_r($GLOBALS), which allows you to visually see that it is there, but there is no way to programmatically detect it (other than capturing the output of print_r and parsing it--ugly!)

Problem also occurs on a SuSE 9.3 Linux box (Linux kernel v. 2.6.5-7.147-smp) running PHP 4.3.9

Reproduce code:
---------------
$arrayOfStuff = array("stuff" => "valueOfStuff");

echo isset($stuff).", ".isset($GLOBALS["stuff"]).", $stuff\n";

// Commenting out the globalStuff() call produces the 
// expected result

globalStuff();
extract($arrayOfStuff, EXTR_SKIP);

echo isset($stuff).", ".isset($GLOBALS["stuff"]).", $stuff\n";

function globalStuff() {
    global $stuff;
}

Expected result:
----------------
, , 
1, 1, valueOfStuff


Actual result:
--------------
, , 
, ,