The changes for PYTHON-1154 changed setup.py to call sphinx.main directly. Sphinx 1.3+ calls sys.exit in sphinx.main(), denying us the ability to check return status and print the path to the built docs.

Change setup.py to call sphinx.build_main when available (Sphinx 1.3+), and fallback to sphinx.main otherwise.

This is truly a trivial bug. Sphinx still tells you why a build fails. We just can't print the path to the built docs anymore, a trivial regression that likely impacts no one.