_redirects now handles rewrites and per-section 404 pages

Two statuses that _redirects used to skip now work, on Level 0 sites.

200 serves another page at the same address. The visitor’s address doesn’t change; they get the target’s content. The common use is a single-page app, where every route is handled by one page:

/*    /index.html    200

404 serves a section’s own not-found page, with a 404 status:

/docs/*    /docs/404.html    404

A change to existing rules

A rule now gives way to a real file. If a file exists at a rule’s source path, the file is served and the rule is skipped, the same as on Netlify. That applies to 301 and 302 rules as well as the new ones, so a redirect whose source is a real file stops firing. To make a rule win anyway, add ! to its status:

/old-page.html    /new-page/    301!

Worth knowing

• Directory pages and the trailing-slash option. With # ee:trailing-slash on left out, a request for /about that has an /about/index.html behind it now gets your 404 rule’s page, not a bare 404.
• A rewrite target can’t be cached as immutable. Content served at an address that isn’t its own is cached like any other file, never for a year, so the next deploy is picked up.