Resolve some issue with tox.ini, setup.cfg

- Use constraints for documentation targets
- Indicate support for Python 3.6, 3.7
- Fix indentation

Change-Id: I486b6f645fa71f0fa519464465bf26411ca4faf4
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

setup.cfg

@@ -13,20 +13,20 @@ project_urls =
     Source Code = https://git.openstack.org/cgit/openstack-dev/pbr/
 requires-python = >=2.6
 classifier =
-        Development Status :: 5 - Production/Stable
-        Environment :: Console
-        Environment :: OpenStack
-        Intended Audience :: Developers
-        Intended Audience :: Information Technology
-        License :: OSI Approved :: Apache Software License
-        Operating System :: OS Independent
-        Programming Language :: Python
-        Programming Language :: Python :: 2
-        Programming Language :: Python :: 2.7
-        Programming Language :: Python :: 3
-        Programming Language :: Python :: 3.3
-        Programming Language :: Python :: 3.4
-        Programming Language :: Python :: 3.5
+    Development Status :: 5 - Production/Stable
+    Environment :: Console
+    Environment :: OpenStack
+    Intended Audience :: Developers
+    Intended Audience :: Information Technology
+    License :: OSI Approved :: Apache Software License
+    Operating System :: OS Independent
+    Programming Language :: Python
+    Programming Language :: Python :: 2
+    Programming Language :: Python :: 2.7
+    Programming Language :: Python :: 3
+    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
 
 [files]
 packages =

tox.ini

@@ -1,12 +1,11 @@
 [tox]
 minversion = 3.1
-envlist = pep8,py{37,36,35,27},docs
+envlist = pep8,py27,py36,py37,docs
 ignore_basepython_conflict = True
-skip_missing_interpreters = True
 
 [testenv]
 usedevelop = True
-install_command = pip install {opts} {packages}
+basepython = python3
 passenv = PBR_INTEGRATION PIPFLAGS PIPVERSION PBRVERSION REPODIR WHEELHOUSE PROJECTS
 setenv =
   OS_STDOUT_CAPTURE={env:OS_STDOUT_CAPTURE:1}
@@ -18,11 +17,9 @@ deps =
 commands = stestr run --suppress-attachments {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:docs]
-basepython = python3
 whitelist_externals = rm
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
@@ -32,21 +29,16 @@ commands =
   sphinx-build -W -b html doc/source doc/build/html {posargs}
 
 [testenv:releasenotes]
-basepython = python3
 whitelist_externals = rm
-deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
-  -r{toxinidir}/doc/requirements.txt
+deps = {[testenv:docs]deps}
 commands =
   rm -rf releasenotes/build
   sphinx-build -W -b html -d releasenotes/build/doctrees releasenotes/source releasenotes/build/html
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
   PYTHON=coverage run --source pbr --parallel-mode
 commands =
@@ -64,7 +56,6 @@ exclude = .venv,.tox,dist,doc,*.egg,build
 show-source = true
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt