Cannot define more than one theme when using the new setuptools plugin mechanism
When an egg defines themes accessible through the new 'sphinx_themes' entry point, it is not possible to define more than one theme. Only one theme is registered in Sphinx, other themes are simply ignored.
After some investigation, in file theming.py, method load_extra_themes, the line 75:
cls.themes[theme] = (path.join(themedir, theme), None)
is not correctly indented. Simply adding one indent fixes the problem.