diff --git a/ansible/group_vars/all b/ansible/group_vars/all
index 3cd8c82..37a59ca 100644
--- a/ansible/group_vars/all
+++ b/ansible/group_vars/all
@@ -5,5 +5,6 @@ virtualenv_path: "{{ '/'.join([ansible_facts.env['HOME'], 'tenks-venv']) }}"
 
 # The URL of the upper constraints file to pass to pip when installing Python
 # packages.
+# NOTE: Python 2 support dropped in Ussuri, Python 3.6 support dropped in Zed.
 python_upper_constraints_url: >-
-  https://releases.openstack.org/constraints/upper/{% if ansible_facts.python.version.major == 2 %}train{% else %}master{% endif %}
+  https://releases.openstack.org/constraints/upper/{% if ansible_facts.python.version.major == 2 %}train{% elif ansible_facts.python.version.minor <= 6 %}yoga{% else %}master{% endif %}
diff --git a/zuul.d/jobs.yaml b/zuul.d/jobs.yaml
index beb4a60..5d16cfe 100644
--- a/zuul.d/jobs.yaml
+++ b/zuul.d/jobs.yaml
@@ -17,6 +17,10 @@
     name: tenks-deploy-teardown-ovs-bios-centos8s
     parent: tenks-deploy-teardown-ovs-bios-base
     nodeset: centos-8-stream
+    required-projects:
+      # NOTE(mgoddard): CentOS 8 uses Python 3.6 which is not supported in Zed.
+      - name: openstack/requirements
+        override-checkout: stable/yoga
 
 - job:
     name: tenks-deploy-teardown-ovs-bios-debian
@@ -32,6 +36,10 @@
     name: tenks-deploy-teardown-linuxbridge-uefi-centos8s
     parent: tenks-deploy-teardown-linuxbridge-uefi-base
     nodeset: centos-8-stream
+    required-projects:
+      # NOTE(mgoddard): CentOS 8 uses Python 3.6 which is not supported in Zed.
+      - name: openstack/requirements
+        override-checkout: stable/yoga
 
 - job:
     name: tenks-deploy-teardown-linuxbridge-uefi-debian