Updated from global requirements

OpenStack Proposal Bot · OpenStack Proposal Bot · commit 001efadbdef4 · 2018-01-18T03:30:37.000Z
Change-Id: Ic5715c21e19d92c8f3d85091bfa41c28bb271c42
diff --git a/doc/requirements.txt b/doc/requirements.txt
@@ -3,4 +3,4 @@
 # process, which may cause wedges in the gate later.
 openstackdocstheme>=1.17.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
-sphinx>=1.6.2 # BSD
+sphinx!=1.6.6,>=1.6.2 # BSD
