New Sphinx with extra values to unpack

I doubt this will pass the tests with the current version of sphinx installed by conda (v1.2.2) but when the new version become available (which is already through pip), a `ValueError:  too many values to unpack` will be raised unless a new element is unpacked.   This PR add an extra variable to unpack all the elements properly.

In case you are interested, this was introduced in Sphinx by [this commit](https://bitbucket.org/birkenfeld/sphinx/commits/f4743ba9521feb16bedc98f29275868054f01d67)