RHEL5 kickstart needs to mount cdrom in postinst

[Chris Lumens]

> Wow! It worked. Many thanks for all the help. I added the updates.img
> file into the tree on the CD and created a new CD. It now runs
> postinstall without ejecting the CD.

Good, thanks for confirming my fix works.  I'll try to get this into U2.
I find it amazing that no one ran into this during testing or the beta
cycles, but sometimes things get overlooked.

- Chris