pin pip to pre-pep 517

Waiting for pypa/pip#9446
to be resolved we will pin pip to 19.3.1 for now

this still might not work because it might need
newer virtualenv and tox installations on containers
to work.  it's very hard to follow which tool does
what under what conditions.

roles/scripts/templates/openstack.sh.j2

@@ -72,7 +72,11 @@ setup ()
 
     export UPPER_CONSTRAINTS_FILE=${WORKSPACE}/upper_constraints.txt
     export SPECIAL_REQUIREMENTS_FILE=${WORKSPACE}/special_requirements.txt
-    export TOX_TESTENV_PASSENV="UPPER_CONSTRAINTS_FILE ${TOX_TESTENV_PASSENV}"
+    export TOX_TESTENV_PASSENV="UPPER_CONSTRAINTS_FILE VIRTUALENV_PIP ${TOX_TESTENV_PASSENV}"
+
+    # wait for https://github.com/pypa/pip/issues/9446
+    # to be resolved before removing
+    export VIRTUALENV_PIP=19.3.1
 
     curl --retry 3 "$UPPER_CONSTRAINTS" -L --insecure --progress-bar --output ${UPPER_CONSTRAINTS_FILE}
 
@@ -304,6 +308,8 @@ run_project ()
 
     sed -i.tmp "s#-r{toxinidir}/requirements.txt#-r{toxinidir}/requirements.txt\n      -r${SPECIAL_REQUIREMENTS_FILE}#" tox.ini
 
+    sed  -i.tmp '/testenv]$/a download = True' tox.ini
+
     for keyword in SQLAlchemy alembic dogpile.cache oslo.db oslo.cache sqlalchemy-migrate greenlet ; do
         sed -i.tmp "s/^${keyword}.*//" requirements.txt
     done
@@ -350,30 +356,30 @@ run_projects() {
         if [ "${proj}" = "oslo.db" ]; then
             prepare_openstack_project oslo.db
             OS_TEST_TIMEOUT=0
-            run_project oslo.db py37
-            gen_junit_results oslo.db py37
+            run_project oslo.db py3
+            gen_junit_results oslo.db py3
             handle_exit
 
         elif [ "${proj}" = "keystone" ]; then
             prepare_openstack_project keystone
             OS_TEST_TIMEOUT=600
-            find ${WORKSPACE}/keystone/keystone/tests/ -path "*/tmp/*" -type d -exec rm -fr {} \;
-            run_project keystone py37 'keystone.tests.unit.*sql.*'
-            gen_junit_results keystone py37
+            find ${WORKSPACE}/keystone/keystone/tests/ -name tmp -type d -exec rm -fr {} \;
+            run_project keystone py3 'keystone.tests.unit.*sql.*'
+            gen_junit_results keystone py3
             handle_exit
 
         elif [ "${proj}" = "nova" ]; then
             prepare_openstack_project nova
             OS_TEST_TIMEOUT=400
-            run_project nova py37 'nova.tests.unit.db'
-            gen_junit_results nova py37
+            run_project nova py3 'nova.tests.unit.db'
+            gen_junit_results nova py3
             handle_exit
 
         elif [ "${proj}" = "neutron" ]; then
             prepare_openstack_project neutron
             OS_TEST_TIMEOUT=0
-            run_project neutron py37 ".*\.unit\.db\."
-            gen_junit_results neutron py37 unit
+            run_project neutron py3 ".*\.unit\.db\."
+            gen_junit_results neutron py3 unit
             handle_exit
 
             # NOTE: the "functional" suite sets the test path to