* Treat _index.LANG.md as section, not page (close#1694)
Display more advanced information in case of a future crash here
* Add link to translated local section in test_site_i18n to catch #1694
It appears linking to another translated page does not trigger the bug,
but linking to a section within the same (translated) page does.
* Allow (and test for) homepage internal links in broken link detection
Co-authored-by: southerntofu <southerntofu@thunix.net>