Add devstack/f20 experimental test

Add experimental-tempest-dsvm-f20 test and run it with devstack
experimental tests.

The initial idea with this change is to validate devstack-f20 nodes
(added with [1]) with a tempest run on some devstack changes.  Once
this has been proven stable we hope to promote it to a check job, and
eventaully vote.

Tested that jenkins-jobs correctly builds the
experimental-tempest-dsvm-f20 job.

[1] https://review.openstack.org/#/c/86842/

Change-Id: I6ed30a3ba1268476be1a0f16b97a4ea44b1ecec2

modules/openstack_project/files/jenkins_job_builder/config/devstack-gate.yaml

@@ -1181,6 +1181,35 @@
       - devstack-logs
       - console-log
 
+# experimental test for validating devstack changes on f20 & testing
+# devstack-f20 nodes
+- job:
+    name: 'experimental-devstack-tempest-dsvm-f20'
+    node: 'devstack-f20'
+
+    wrappers:
+      - timeout:
+          timeout: 125
+          fail: true
+      - timestamps
+
+    builders:
+      - link-logs
+      - net-info
+      - devstack-checkout
+      - shell: |
+          #!/bin/bash -xe
+          export PYTHONUNBUFFERED=true
+          export DEVSTACK_GATE_TIMEOUT=120
+          export DEVSTACK_GATE_TEMPEST=1
+          export DEVSTACK_GATE_SMOKE_SERIAL=1
+
+          cp devstack-gate/devstack-vm-gate-wrap.sh ./safe-devstack-vm-gate-wrap.sh
+          ./safe-devstack-vm-gate-wrap.sh
+
+    publishers:
+      - devstack-logs
+      - console-log
 
 - job:
     name: gate-devstack-gate-unittests

modules/openstack_project/files/zuul/layout.yaml

@@ -412,6 +412,8 @@ jobs:
     voting: false
   - name: check-tempest-dsvm-cells-full
     voting: false
+  - name: experimental-devstack-tempest-dsvm-f20
+    voting: false
 # For Gerrit ver 2.4.x (using maven)
   - name: ^(gate|check)-gerrit-unittests$
     branch: ^openstack/2\.4.*$
@@ -2519,6 +2521,7 @@ projects:
       - gate-grenade-dsvm-forward
       - check-tempest-master-dsvm-full-havana
       - check-tempest-master-dsvm-neutron-havana
+      - experimental-devstack-tempest-dsvm-f20
 
   - name: openstack-dev/grenade
     check: