YOURLS plugin : 404 if not found

By default and by design, when a requested short URL is not found, YOURLS redirects to the site root with a "302 temporary redirect" header.

From the source:

yourls_redirect( YOURLS_SITE, 302 ); // no 404 to tell browser this might change,
                                     // and also to not pollute logs

This plugin outputs a default "404 not found" error page instead.

Installation

1. In /user/plugins, create a new folder named 404-if-not-found.
2. Drop these files in that directory.
3. Go to the Plugins administration page (eg. http://sho.rt/admin/plugins.php) and activate the plugin.
4. Have fun!

License

Do whatever the hell you want with this.