/problem/xyz inappropriately redirects to front page

[Matthew Paul Thomas]

1. Go to <https://errors.ubuntu.com/testing-the-404-page>.
2. Go to <https://errors.ubuntu.com/problem/testing-the-404-page>.

What happens:
1. The site returns 404 Not Found and shows an error page.
2. The site returns 302 Found and redirects to the front page with an error message at the top.

What should happen:
2. The site returns 404 Not Found and shows an error page.

Returning 302 Found may mislead search engines, link checkers, etc into thinking that the page exists. And redirecting to the front page may disorient users, error message notwithstanding.