tox: Keeping going with docs

Sphinx 1.8 introduced [1] the '--keep-going' argument which, as its name
suggests, keeps the build running when it encounters non-fatal errors.
This is exceptionally useful in avoiding a continuous edit-build loop
when undertaking large doc reworks where multiple errors may be
introduced.

[1] https://github.com/sphinx-doc/sphinx/commit/e3483e9b045

Change-Id: Icfd0be4aff2de88346cfe380c29f28d16538733c

lower-constraints.txt

@@ -96,7 +96,7 @@ simplejson==3.5.1
 six==1.10.0
 smmap==0.9.0
 snowballstemmer==1.2.1
-Sphinx==1.6.2
+Sphinx==1.8.0
 sphinxcontrib-websupport==1.0.1
 stestr==2.0.0
 stevedore==1.20.0

test-requirements.txt

@@ -7,8 +7,8 @@ openstackdocstheme>=1.20.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 docutils>=0.11 # OSI-Approved Open Source, Public Domain
 python-subunit>=1.0.0 # Apache-2.0/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
+sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
+sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
 oslotest>=3.2.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD

tools/releasenotes_tox.sh

@@ -2,7 +2,7 @@
 
 rm -rf releasenotes/build
 
-sphinx-build -a -E -W \
+sphinx-build -a -E -W --keep-going \
     -d releasenotes/build/doctrees \
     -b html \
     releasenotes/source releasenotes/build/html

tox.ini

@@ -65,7 +65,8 @@ commands =
 
 [testenv:docs]
 basepython = python3
-commands = python setup.py build_sphinx
+commands =
+  sphinx-build -W --keep-going -b html -d doc/build/doctrees doc/source doc/build/html
 
 [testenv:debug]
 basepython = python3