tox: Trivial cleanup

Move 'basepython' to the top-level 'testenv'.

Change-Id: I13e72ec6cbd006ca6eccfe21f2a0584e86a52669

tox.ini

@@ -1,8 +1,10 @@
 [tox]
-minversion = 2.0
+minversion = 3.1
 envlist = py27,py37,pep8
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
 passenv = OS_*
@@ -16,14 +18,12 @@ deps =
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8
   # run security linter
   bandit -r oslo_messaging -x tests -n5
 
 [testenv:cover]
-basepython = python3
 setenv =
     PYTHON=coverage run --source oslo_messaging --parallel-mode
 commands =
@@ -33,11 +33,9 @@ commands =
   coverage report
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 whitelist_externals = rm
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
@@ -45,21 +43,18 @@ commands =
   sphinx-build -W --keep-going -b html doc/source doc/build/html
 
 [testenv:py27-func-rabbit]
-basepython = python2.7
 setenv =
     {[testenv]setenv}
     TRANSPORT_DRIVER=rabbit
 commands = pifpaf run rabbitmq --  stestr run --slowest {posargs:oslo_messaging.tests.functional}
 
 [testenv:py36-func-rabbit]
-basepython = python3.6
 setenv =
     {[testenv]setenv}
     TRANSPORT_DRIVER=rabbit
 commands = pifpaf run rabbitmq --  stestr run --slowest {posargs:oslo_messaging.tests.functional}
 
 [testenv:py27-func-kafka]
-basepython = python2.7
 setenv =
     {[testenv]setenv}
     TRANSPORT_URL=kafka://127.0.0.1:9092/
@@ -67,7 +62,6 @@ setenv =
 commands = {toxinidir}/setup-test-env-kafka.sh stestr run --slowest {posargs:oslo_messaging.tests.functional}
 
 [testenv:py27-func-amqp1]
-basepython = python2.7
 setenv =
     {[testenv]setenv}
     TRANSPORT_URL=amqp://stackqpid:secretqpid@127.0.0.1:5672//
@@ -76,7 +70,6 @@ setenv =
 commands = {toxinidir}/tools/setup-test-env-amqp1.sh stestr run --slowest {posargs:oslo_messaging.tests.functional}
 
 [testenv:py36-func-amqp1]
-basepython = python3.6
 setenv =
     {[testenv]setenv}
     TRANSPORT_URL=amqp://stackqpid:secretqpid@127.0.0.1:5672//
@@ -85,7 +78,6 @@ setenv =
 commands = {toxinidir}/tools/setup-test-env-amqp1.sh stestr run --slowest {posargs:oslo_messaging.tests.functional}
 
 [testenv:py36-func-kafka]
-basepython = python3.6
 setenv =
     {[testenv]setenv}
     TRANSPORT_URL=kafka://127.0.0.1:9092/
@@ -96,7 +88,6 @@ commands = {toxinidir}/setup-test-env-kafka.sh stestr run --slowest {posargs:osl
 [testenv:bandit]
 # NOTE(kgiusti): This is required for the integration test job of the bandit
 # project. Please do not remove.
-basepython = python3
 commands = bandit -r oslo_messaging -x tests -n5
 
 [flake8]
@@ -113,7 +104,6 @@ import_exceptions =
 local-check-factory = oslo_messaging.hacking.checks.factory
 
 [testenv:releasenotes]
-basepython = python3
 whitelist_externals = rm
 commands =
   rm -rf releasenotes/build
@@ -121,12 +111,10 @@ commands =
 deps = -r{toxinidir}/doc/requirements.txt
 
 [testenv:bindep]
-basepython = python3
 deps = bindep
 commands = bindep {posargs}
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt