appln which is cached (user cache) in 1.5.0 is moving to system cache when upgraded to 6.0

Tested OS : All
Tested Build : mustang PIT build 52

Steps to reproduce :

1. Install tiger update 05 and mustang PIT build 52
2. Clear cache (\rm -rf ~/.java)
3. Clear system cache ( \rm -rf /tmp/malathi/test)
4. configure system cache
 /jre1.5.0_05/bin/javaws -userConfig deployment.system.cachedir /tmp/malathi/test
5. import notepad appln into system cache
/jre1.5.0_05/bin/javaws -system -import http://java.sun.com/products/javawebstart/apps/notepad.jnlp
6. Import mg appln into user cache
/jre1.5.0_05/bin/javaws http://java.sun.com/products/javawebstart/apps/mg.jnlp
7. Launch cache viewer /jre1.5.0_05/bin/javaws -viewer
mg appln is listed under Applications and notepad appln is listed under system applications
8. Upgrade the system cache to 6.0 using /jre1.6.0/bin/javaws -system
The popup "please wait while the user cache is updated to 6.0" is displayed
9. Launch /jre1.6.0/bin/javaws -viewer

Now mg appln is listed under system applications and nothing is listed under applications