new HttpSession gets old 'unique' session_id (Bug in WAS4.0.x ???) -- WEB400

After a couple of day's
- struggling with session
- upgrading our webserver to WAS v4.0.5
- creating some 'testcode'

I only could conclude that there must be a bug in WAS v4.0.x (surprise...)

This is what happens:
Invalidating and recreating an HttpSession returns the old 'unique'
session_id where another new 'unique' session_id should be created.

*******************
anyone has a fix for this?
*******************


This is the testcode:
--------------------
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
System.out.println("**** Servlet reactivated");
session = req.getSession(true);
if (!(session.isNew()))
{
System.out.println("next entry, session already active, SESSIONID = " +
session.getId());
session.invalidate();
session = req.getSession(true);
if (session.isNew())
{
System.out.println("next entry, new session created, SESSIONID = " +
session.getId());
}
else
{
System.out.println("next entry, no new session created, SESSIONID = " +
session.getId());
}
}
else
{
System.out.println("First entry, new session created, SESSIONID = " +
session.getId());
}
// Send resultingpage
getServletConfig().getServletContext().getRequestDispatcher("index.html").fo
rward(req, res);
System.out.println("**** Exit Servlet");
}

This is the indexpage:
---------------------
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<META name="GENERATOR" content="IBM WebSphere Studio">
<TITLE>index.html</TITLE>
</HEAD>
<BODY>
<FORM method="POST" action="TestServlet">
<INPUT type="submit" name="test">
</FORM>
</BODY>
</HTML>

This is the result on console after 'submitting' a couple of times:
----------------------------
[1/23/03 17:04:19:614 CET] 518bb721 SystemOut U WSRU0069I: Applications 
and
modules were successfully restarted.
[1/23/03 17:04:41:646 CET] 2446373e WebGroup I SRVE0091I: [Servlet LOG]:
TestServlet: init
[1/23/03 17:04:41:646 CET] 2446373e SystemOut U **** Servlet reactivated
[1/23/03 17:04:41:656 CET] 2446373e SystemOut U First entry, new session
created, SESSIONID = IUN33VCPPD3ZK0LT0HK3CWA
[1/23/03 17:04:41:686 CET] 2446373e SystemOut U **** Exit Servlet
[1/23/03 17:05:12:400 CET] 2446373e SystemOut U **** Servlet reactivated
[1/23/03 17:05:12:400 CET] 2446373e SystemOut U next entry, session 
already
active, SESSIONID = IUN33VCPPD3ZK0LT0HK3CWA
[1/23/03 17:05:12:410 CET] 2446373e SystemOut U next entry, new session
created, SESSIONID = IUN33VCPPD3ZK0LT0HK3CWA
[1/23/03 17:05:12:430 CET] 2446373e SystemOut U **** Exit Servlet
[1/23/03 17:05:29:385 CET] 2446373e SystemOut U **** Servlet reactivated
[1/23/03 17:05:29:385 CET] 2446373e SystemOut U next entry, session 
already
active, SESSIONID = IUN33VCPPD3ZK0LT0HK3CWA
[1/23/03 17:05:29:395 CET] 2446373e SystemOut U next entry, new session
created, SESSIONID = IUN33VCPPD3ZK0LT0HK3CWA
[1/23/03 17:05:29:415 CET] 2446373e SystemOut U **** Exit Servlet