Use upper-constraints for tox envs

Pin tox environments to upper-constraints to avoid conflicts with
library releases.

Change-Id: I6e564f3035e2fdc5461f57f15168f498c99fc164
Closes-Bug:#1628597
diff --git a/tox.ini b/tox.ini
index d8d390e..0143193 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,6 +8,8 @@
 setenv =
     VIRTUAL_ENV={envdir}
     OS_TEST_PATH=./tempest/test_discover
+    BRANCH_NAME=master
+    CLIENT_NAME=tempest
 deps =
     setuptools
     -r{toxinidir}/requirements.txt
@@ -17,9 +19,12 @@
     VIRTUAL_ENV={envdir}
     OS_TEST_PATH=./tempest/tests
     PYTHONWARNINGS=default::DeprecationWarning
-passenv = OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_TEST_TIMEOUT OS_TEST_LOCK_PATH OS_TEST_PATH TEMPEST_CONFIG TEMPEST_CONFIG_DIR http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
+    BRANCH_NAME=master
+    CLIENT_NAME=tempest
+passenv = OS_STDOUT_CAPTURE OS_STDERR_CAPTURE OS_TEST_TIMEOUT OS_TEST_LOCK_PATH OS_TEST_PATH TEMPEST_CONFIG TEMPEST_CONFIG_DIR http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY ZUUL_CACHE_DIR REQUIREMENTS_PIP_LOCATION
 usedevelop = True
-install_command = pip install -U {opts} {packages}
+install_command =
+    {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 whitelist_externals = *
 deps =
     -r{toxinidir}/requirements.txt