Description:
------------
It appears that enabling fastcgi.impersonate on Windows in PHP 5.3.x does not 
actually impersonate the calling user when using exec() or similar.

I would just get messages saying "Cannot fork", whereas in PHP 5.2.x there was no 
such error.

Turning off fastcgi.impersonate fixed this issue, as IIS seems to run PHP in the 
user context of the worker process anyway.

Test script:
---------------
<?

// This will fail when fastcgi.impersonate = 1 in PHP 5.3.x
exec("c:\\path\\to\\executable.exe");

Expected result:
----------------
The file should be successfully executed if the worker process user has permission 
to access the EXE.

Actual result:
--------------
Regardless of worker process permissions, an error message saying:

"Warning: exec() [function.exec]: Unable to fork [c:\path\to\executable.exe]"

is encountered.