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: I806842ce6d2522deab060f5e9ef6607a1e919dbf

lower-constraints.txt

@@ -136,7 +136,7 @@ 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
 sqlalchemy-migrate==0.11.0
 SQLAlchemy==1.0.10

test-requirements.txt

@@ -6,8 +6,8 @@ openstackdocstheme>=1.18.1 # Apache-2.0
 PyYAML>=3.12 # MIT
 Jinja2>=2.10 # BSD License (3 clause)
 six>=1.10.0 # MIT
-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>=1.8.0,<2.0.0;python_version=='2.7' # BSD
+sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
 reno>=2.5.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # 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

@@ -66,6 +66,8 @@ commands = python ./tools/process-templates.py -c
 
 [testenv:releasenotes]
 basepython = python3
+whitelist_externals =
+    bash
 commands = bash -c tools/releasenotes_tox.sh
 
 [testenv:cover]