Sync Sphinx requirement
Sync sphinx dependency with global requirements. It caps python 2 since
sphinx 2.0 no longer supports Python 2.7.
Change-Id: I599da0883546c2af9fd054f64bee695a70d823d8
diff --git a/test-requirements.txt b/test-requirements.txt
index 9af8c9c..b2555d0 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -4,7 +4,8 @@
hacking>=1.1.0,<1.2.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
openstackdocstheme>=1.11.0 # Apache-2.0
# releasenotes
reno>=1.8.0 # Apache-2.0