Update TOX_CONSTRAINTS_FILE for stable/zed

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

Change-Id: I3acc0a817f5b8d5425d8d662d1919ac7e3cdaa0d

tox.ini

@@ -9,7 +9,7 @@ usedevelop = True
 setenv =
   PYTHONDONTWRITEBYTECODE=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/zed}
   -r{toxinidir}/test-requirements.txt
   .[ldap,memcache,mongodb]
 commands =
@@ -43,7 +43,7 @@ passenv = FAST8_NUM_COMMITS
 # NOTE(browne): This is required for the integration test job of the bandit
 # project. Please do not remove.
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/zed}
   -r{toxinidir}/requirements.txt
   .[bandit]
 commands = bandit -r keystone -x 'keystone/tests/*'
@@ -85,7 +85,7 @@ passenv =
 
 [testenv:functional]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/zed}
   -r{toxinidir}/test-requirements.txt
 setenv = OS_TEST_PATH=./keystone/tests/functional
 commands =
@@ -123,7 +123,7 @@ max-complexity=24
 
 [testenv:docs]
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/zed}
   -r{toxinidir}/doc/requirements.txt
   .[ldap,memcache,mongodb]
 commands=