Use upper-constraints.txt for tox tests

Change-Id: I18b946269c3452d20205fbba392d7216cf4c92ee

tox.ini

@@ -5,7 +5,7 @@ skipsdist = True
 
 [testenv]
 usedevelop = True
-install_command = pip install {opts} {packages}
+install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=master} {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 setenv =
@@ -36,6 +36,10 @@ commands = rm -rf doc/build
            sphinx-build -E -W -b html doc/source doc/build/html
 
 [testenv:cover]
+# NOTE(kiall): this target does not use constraints because upstream infra does
+#              not yet support it. Once that's fixed, we can drop the
+#              install_command.
+install_command = pip install {opts} {packages}
 commands = python setup.py testr --coverage --testr-args='{posargs}'
 
 [testenv:bandit]
@@ -94,9 +98,17 @@ passenv = TEMPEST_CONFIG
           OS_DEBUG
 
 [testenv:releasenotes]
+# NOTE(kiall): this target does not use constraints because upstream infra does
+#              not yet support it. Once that's fixed, we can drop the
+#              install_command.
+install_command = pip install {opts} {packages}
 commands = sphinx-build -a -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:venv]
+# NOTE(kiall): this target does not use constraints because upstream infra does
+#              not yet support it. Once that's fixed, we can drop the
+#              install_command.
+install_command = pip install {opts} {packages}
 commands = {posargs}
 
 [flake8]