Blacklist sphinx 2.1.0 (autodoc bug)
See for upstream details
@@ -7,7 +7,7 @@ coverage!=4.4,>=4.0 # Apache-2.0
ddt>=1.0.1 # MIT
reno>=2.5.0 # Apache-2.0
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,>=1.6.2;python_version>='3.4' # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
openstackdocstheme>=1.20.0 # Apache-2.0
oslotest>=3.2.0 # Apache-2.0
testscenarios>=0.4 # Apache-2.0/BSD
