Update UPPER_CONSTRAINTS_FILE for stable/ocata

Change-Id: I5eb6320d61ac4fdeb8f5db9eb724a9c3b7fa731c

Author: openstackadmin

tox.ini

@@ -17,7 +17,7 @@ passenv =  http_proxy
            NO_PROXY
 deps = -r{toxinidir}/test-requirements.txt
        -r{toxinidir}/requirements.txt
-install_command = {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
+install_command = {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/ocata} {opts} {packages}
 whitelist_externals = find
 commands =
     find . -type f -name "*.pyc" -delete