.. note::

   $ find sphinx tests LICENSE doc/conf.py -type f -exec sed -i '' -e 's/2007\-20../2007-2021/' {} \;
   $ git co sphinx/locale/**/*.js sphinx/templates/epub3/mimetype

Split testing of changes builder to its own test file and root.
Improve coverage a little, and add case that fails if a module
directive is included in the rst source.

Correctly handle changesets with a module declared.

Fixes https://github.com/sphinx-doc/sphinx/issues/6134