Update UPPER_CONSTRAINTS_FILE for stable/stein

Update the URL to the upper-constraints file to point to the redirect
rule on releases.openstack.org so that anyone working on this branch
will switch to the correct upper-constraints list automatically when
the requirements repository branches.

Until the requirements repository has as stable/stein branch, tests will
continue to use the upper-constraints list on master.

Change-Id: Iec9ae34f9496baa3b522bc9ae2337bf7e3922ac0

tox.ini

@@ -14,7 +14,7 @@ passenv = ZUUL_CACHE_DIR
           REQUIREMENTS_PIP_LOCATION
 install_command = pip install {opts} {packages}
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/stein}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands =
@@ -32,7 +32,7 @@ commands = bandit -r novaclient -n5 -x tests
 [testenv:venv]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/stein}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
@@ -41,7 +41,7 @@ commands = {posargs}
 [testenv:docs]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/stein}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands =
@@ -53,7 +53,7 @@ commands =
 [testenv:releasenotes]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/stein}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands =