Lots of detail in simonw/datasette-search-all#2 - short version is that I have a plugin with its own index.html template and Datasette intermittently fails to load it and uses the default index.html that ships with Datasette instead.

Related:

• "Templates considered" comment broken in >=0.35 #689: "Templates considered" comment broken in >=0.35
• Variables from extra_template_vars() not exposed in _context=1 #693: Variables from extra_template_vars() not exposed in _context=1 (may as well fix this while I'm in there)