Merge "fix tox python3 overrides"

tox.ini

@@ -17,9 +17,11 @@ deps =
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
+basepython = python3
 commands = flake8
 
 [testenv:venv]
+basepython = python3
 commands = {posargs}
 
 [pbr]
@@ -50,6 +52,7 @@ commands =
     stestr run --slowest {posargs}
 
 [testenv:cover]
+basepython = python3
 setenv =
     PYTHON=coverage run --source glanceclient --parallel-mode
 commands =
@@ -59,11 +62,13 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
   sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
+basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html