I dunno; what you're asking for doesn't really make sense. If the actual chroot is put into user2's .shellrc, he could exit out of it whenever...?
If you want to get back out to the main filesystem, a chroot isn't what you want. Think about this - it's designed to limit users. Conversations about how to get out of a chroot are typically discussions of why you shouldn't be relying on this for security, not how to add more functionality to it.