1. Make a forum which contains 2 pages of messages. the second page should have
just a single discussion.

2. Go to second page.

3. Go into the discussion. Move it to another forum.

4. Back to the first forum. Because it remembers the page number, you get an
error about invalid page number.

Maybe we should make it so that if you try to access a page number > max, it
changes the stored value to be the last existing page?