Update sphinx to 1.7.9

[pyup-bot]

This PR updates Sphinx from 1.7.8 to 1.7.9.

Changelog

1.7.9

=====================================

Features added
--------------

* 5359: Make generated texinfo files reproducible by sorting the anchors

Bugs fixed
----------

* 5361: crashed on incremental build if document uses include directive

Links

• PyPI: https://pypi.org/project/sphinx
• Changelog: https://pyup.io/changelogs/sphinx/
• Homepage: http://sphinx-doc.org/

[coveralls]

Pull Request Test Coverage Report for Build 156

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.674%

---

Totals
Change from base Build 153:	0.0%
Covered Lines:	126
Relevant Lines:	129

---

💛 - Coveralls