Sphinx is a tool that translates a set of reStructuredText source files into
various output formats, including HTML, ePub, LaTeX and plain text. Sphinx was
originally created for the Python documentation, but it has excellent
facilities for the documentation of software projects in a range of languages.

All Sphinx dependencies must be built with Python 3 support and since there are
many different way of providing this, the following packages require special
build instructions not captured in REQUIRES:
- python/python-urllib3: install python/python3 first
- python-idna: install python/python3 first
- python/python-chardet: install python/python3 first
- python/imagesize: install python/python3 first
- python/alabaster: install python/python3 first
- python/python-requests: install python/python3-certifi first
- python/pytz: install python/python3 first and use PYTHON3=yes as a build
  option