Description:
------------
When I created a lib.inc.php that has a few functions defined (e.g. getmicrocode(), myfunction()) and try to include it on several files with require_once, it somehow included more than once even though the end result of 'path/filename' is identical.

My understanding of require_once limitation on Windows (or non-POSIX) platform was that if you have mixed case with the same file name, it will be included again. Another words, as long as you have identical "path/filename" as part of require_once statement, it should include only once.

As a result, since you cannot redeclare the same function within the page, you get:

Fatal error: Cannot redeclare "functionname()" (previously declared in...



Reproduce code:
---------------
For example,

On lib.inc.php:
===============
myfunction1() 
{ echo "hello!";}

myfunction2() 
{ echo "hello again!";}

On index.php 
============
$_my_absolute_path = 'c:/inetpub/wwwroot/';

require_once($_my_absolute_path.'lib.inc.php');
require_once($_my_absolute_path.'template.inc.php');
   
on template.inc.php
===================
$_my_absolute_path = 'c:/inetpub/wwwroot/';

require_once($_my_absolute_path.'lib.inc.php'); // Just in case someone didn't call this previously

The realistic code is quite complex: 
A require_once B and C
B require_once C and *D*
C require_once *D*

and *D* causes redeclare issue when I load A.


Expected result:
----------------
the second attempt to include lib.inc.php by using require_once should be ignored because it was already loaded. 

The same code running on Linux works perfectly and it used to be fine on PHP 4.3.10

But right after I rebuild the server with PHP 5.0.4, I got the following error:

Fatal error: Cannot redeclare myfunction1() (previously declared in...



Actual result:
--------------
the second attempt to include lib.inc.php by using require_once WAS performed and it causes error.