Update TOX/UPPER_CONSTRAINTS_FILE for stable/train

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/train branch, tests will
continue to use the upper-constraints list on master.

Change-Id: I3a1c2ca70c5c7f77f9e52a77dd3aac64cb46a9d1

tox.ini

@@ -13,7 +13,7 @@ passenv = ZUUL_CACHE_DIR
           REQUIREMENTS_PIP_LOCATION
 install_command = pip install {opts} {packages}
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/train}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands =
@@ -31,7 +31,7 @@ commands = bandit -r novaclient -n5 -x tests
 [testenv:venv]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/train}
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
@@ -40,7 +40,7 @@ commands = {posargs}
 [testenv:docs]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/train}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands =
@@ -52,7 +52,7 @@ commands =
 [testenv:releasenotes]
 basepython = python3
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/train}
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands =