fix tox python3 overrides

We want to default to running all tox environments under python 3, so
set the basepython value in each environment.

We do not want to specify a minor version number, because we do not
want to have to update the file every time we upgrade python.

We do not want to set the override once in testenv, because that
breaks the more specific versions used in default environments like
py35 and py36.

Change-Id: I1c8016a76062f21c7413da9fc3d422677a40712e
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

tox.ini

@@ -3,7 +3,6 @@ minversion = 2.0
 envlist = py35,py27,pep8
 
 [testenv]
-basepython = python3
 install_command = pip install {opts} {packages}
 whitelist_externals = find
                       rm
@@ -13,16 +12,15 @@ deps =
   -r{toxinidir}/requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
 
-[testenv:py27]
-basepython = python2.7
-
 [testenv:pep8]
+basepython = python3
 commands =
   flake8
   # Run security linter
   bandit -r oslo_vmware
 
 [testenv:pylint]
+basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
   -r{toxinidir}/test-requirements.txt
@@ -31,19 +29,23 @@ deps =
 commands = pylint oslo
 
 [testenv:bandit]
+basepython = python3
 commands = bandit -r oslo_vmware
 
 [testenv:docs]
+basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:cover]
+basepython = python3
 commands =
   coverage erase
   find . -type f -name "*.pyc" -delete
   python setup.py test --coverage --coverage-package-name=oslo_vmware --testr-args='{posargs}'
   coverage report
-  
+
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [flake8]
@@ -57,9 +59,11 @@ import_exceptions = oslo_vmware.tests.base
 local-check-factory = oslo_vmware.hacking.checks.factory
 
 [testenv:releasenotes]
+basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:lower-constraints]
+basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt