Fix tox.ini to work with ansible 2.2.1.0

Ansible 2.2.1.0 requires included vars files to exist even if the
task/play that includes the file is never run (based on a conditional).

This patch fixes that by ensuring the "upgrade" previous version of
test-vars is fetched for every test.

Change-Id: Ife6dd4a0488765cc9ffd74f11cf8a519d213ea48

tox.ini

@@ -58,6 +58,10 @@ commands =
     bash -c "if [ ! -d "{toxinidir}/tests/common" ]; then \
                git clone https://git.openstack.org/openstack/openstack-ansible-tests {toxinidir}/tests/common; \
              fi"
+    bash -c "if [ ! -d "{toxinidir}/tests/common/previous" ]; then \
+               git clone https://git.openstack.org/openstack/openstack-ansible-tests -b stable/newton \
+                 {toxinidir}/tests/common/previous; \
+             fi"
 
 
 [testenv:pep8]
@@ -118,10 +122,6 @@ setenv =
     ANSIBLE_PARAMETERS=-vvv -e nova_upgrade=True
 commands =
     {[testenv:tests_clone]commands}
-    bash -c "if [ ! -d "{toxinidir}/tests/common/previous" ]; then \
-               git clone https://git.openstack.org/openstack/openstack-ansible-tests -b stable/newton \
-                 {toxinidir}/tests/common/previous; \
-             fi"
     bash -c "{toxinidir}/tests/common/test-ansible-functional.sh"