allow html_theme_path to be provided to sphinx-build
If I run
sphinx-build -b html -D html_theme_path=foo ...
the theme path gets interpreted as
['f', 'o', 'o'] (in https://bitbucket.org/birkenfeld/sphinx/src/6e960412308f/sphinx/theming.py#cl-35)
Is there an alternate way to override the theme path from the command line? I'm trying to build a number of sub-projects together with a common theme.