Hi,
I see that Heiko already fixed this.
Just some background - the build release script contains all necessary information and normally only the script should be modified. But Jenkins evaluates the script only during a build, which is too late to display parameter choices. Choices are updated after a next run of the job. If you need it to update immediately, you can modify the config manually, what is what Heiko did. This config is used just for the next run, it's then overwritten by Jenkins to match the build script. You can see it from the history of config changes - after each manual modification there's a modification by a SYSTEM user.
Ondro