base.html referenced url_for('api_hello'), but that endpoint is now
api_info (/api/info). Since every page extends base.html, the dead
reference raised werkzeug BuildError and returned HTTP 500 site-wide --
including /finger/<user>, which federated Mastodon instances fetch for
link previews. The 500s also defeated nginx's 200-only cache, so every
fetch re-ran the finger subprocess against the daemon on mammut.
pmb