Description:
------------
The manual says that Superglobals can be referenced by variable variables in global scope.

For the $_SERVER superglobal does this only work at it first "normal" usage.

<?php
$Superglobal = '_SERVER';
var_dump($$Superglobal);
?> 

Outputs: NULL

But if i use the $_SERVER Variable after the var_dump(); the var_dump()s output is correct:

<?php
$Superglobal = '_SERVER';
var_dump($$Superglobal);

$_SERVER;

var_dump($$Superglobal);
?> 

Both var_dump()s output the whole $_SERVER array. If i remove the line with $_SERVER; both var_dump()s output is NULL.


Reproduce code:
---------------
<?php
$Superglobal = '_SERVER';
var_dump($$Superglobal);
?> 

Expected result:
----------------
Array containing the $_SERVER variables

Actual result:
--------------
NULL