sitemap.xml not correctly generated for production site

[StevenMaude]

Locally, it works:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
    <url>
         <loc>http://127.0.0.1:8000/</loc>
         <lastmod>2022-12-08</lastmod>
         <changefreq>daily</changefreq>
    </url>
    <url>
         <loc>http://127.0.0.1:8000/access-policies/</loc>
         <lastmod>2022-12-08</lastmod>
         <changefreq>daily</changefreq>
    </url>
…

But on the production site,

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
    <url>
         <loc>None</loc>
         <lastmod>2022-12-08</lastmod>
         <changefreq>daily</changefreq>
    </url>
    <url>
         <loc>None</loc>
         <lastmod>2022-12-08</lastmod>
         <changefreq>daily</changefreq>
    </url>
…

The fix is to specify site_url: https://docs.opensafely.org in mkdocs.yml.

However, I'm not sure we want this setting globally: strictly speaking, for local development and temporary Cloudflare PR, the site URL is different.

It is possible to make this switchable depending on deployment context, as I previously mentioned; I hadn't realised that this issue broke the sitemap.