tox: Keeping going with docs

Change-Id: Id3d18ba8c9b3b87d62fb1e3adca00a96d83c1e4f

test-requirements.txt

@@ -2,7 +2,7 @@ hacking>=1.1.0,<1.2.0 # Apache-2.0
 openstackdocstheme>=1.11.0  # Apache-2.0
 
 oslotest
-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
+sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
+sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
 testrepository>=0.0.18
 reno>=1.8.0 # Apache-2.0

tools/releasenotes_tox.sh

@@ -3,7 +3,7 @@
 rm -rf releasenotes/build
 
 sphinx-build -a -E -W \
-    -d releasenotes/build/doctrees \
+    -d releasenotes/build/doctrees --keep-going \
     -b html \
     releasenotes/source releasenotes/build/html
 BUILD_RESULT=$?