Merge "Use TOX_CONSTRAINTS_FILE"

tox.ini

@@ -13,7 +13,7 @@ setenv =
    OS_STDOUT_CAPTURE=1
    OS_STDERR_CAPTURE=1
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands = stestr run --slowest {posargs}