tox: Move doc8 to docs related envs

Previously doc8 is run as part of pep8 tox env. This leads to some tricky
'deps' in pep8 which installs the docs dependencies. This can be fixed by
moving doc8 to the docs related tox envs (docs and releasenotes).

This also helps developers using devstack avoid hitting an error in
"manage.py compilemessages" in stack.sh. The error is caused by sphinx
installed under .tox directory (as compilemessages tries to compile all
message catalogs even under dot directories like .tox).
Developers sometimes change the horizon code under /opt/stack/horizon
and it is not surprising to run "tox -e pep8".
(I think it is more common compared to a chance to run "tox -e docs".)
Thus I believe it is reasonable to move doc8 to the docs env.

Change-Id: I6345ebbcd24afc358555e9be4b2ca700c4b33861

doc/requirements.txt

@@ -9,6 +9,7 @@ openstackdocstheme>=1.20.0 # Apache-2.0
 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,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
+doc8>=0.6.0 # Apache-2.0
 
 # The below is rewquired to build testing module reference
 mock>=2.0.0 # BSD

lower-constraints.txt

@@ -22,7 +22,6 @@ django-babel==0.6.2
 django-compressor==2.0
 django-debreach==1.4.2
 django-pyscss==2.0.2
-doc8==0.6.0
 docutils==0.11
 dogpile.cache==0.6.2
 dulwich==0.15.0

test-requirements.txt

@@ -12,7 +12,6 @@ hacking>=1.1.0 # Apache-2.0
 astroid==2.1.0;python_version>='3.0' # LGPLv2.1
 bandit!=1.6.0,>=1.4.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
-doc8>=0.6.0 # Apache-2.0
 flake8-import-order==0.12 # LGPLv3
 mock>=2.0.0 # BSD
 mox3>=0.20.0 # Apache-2.0

tox.ini

@@ -37,21 +37,17 @@ deps =
   -r{toxinidir}/requirements.txt
 
 [testenv:venv]
+envdir = {toxworkdir}/venv
 commands = {posargs}
 
 [testenv:pep8]
-# NOTE: Due to doc dependencies, we don't share envdir with "venv".
-# sphinx (precisely Pygments) needs to be installed to make doc8 work properly
-deps =
-  {[testenv]deps}
-  -r{toxinidir}/doc/requirements.txt
+envdir = {toxworkdir}/venv
 setenv =
   DJANGO_SETTINGS_MODULE=openstack_dashboard.test.settings
 commands =
   flake8 {posargs}
   {envpython} {toxinidir}/manage.py extract_messages --verbosity 0 --check-only
   bash {toxinidir}/tools/find_executables.sh
-  doc8 doc/source releasenotes/source releasenotes/notes
   pylint -j 4 --verbose --rcfile=.pylintrc -f colorized openstack_dashboard openstack_auth horizon
 
 [testenv:cover]
@@ -125,6 +121,7 @@ deps =
   -r{toxinidir}/doc/requirements.txt
 commands =
   sphinx-build -W -b html doc/source doc/build/html
+  doc8 doc/source
 
 [testenv:pdf-docs]
 basepython = python3
@@ -141,6 +138,7 @@ envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
+  doc8 doc/source
 
 [testenv:manage]
 envdir = {toxworkdir}/venv