Clarify tempest-full job description

tempest-full is py2 job and only supported until
stable/train as Tempest/devstack or any other OpenStack
service (except swift) are python3-only from ussuri onwards.

This job can be run on ussuri gate onwards for py2.7 test coverage
but it needs to be overridden with stable/train or any stable branch
less than stable/train. Supported nodeset for overridden stable
will be handled by branched devstack.

Also replace few jobs parent from tempest-full to tempest-full-py3.

Change-Id: Icbd0ed88736f0ac746cd1fe20eb9b1f7d739f6bd
diff --git a/.zuul.yaml b/.zuul.yaml
index 5e3f33a..9e67dcc 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -95,6 +95,10 @@
     branches: ^(?!stable/ocata).*$
     description: |
       Base integration test with Neutron networking and py27.
+      This job is supposed to run until stable/train setup only.
+      If you are running it on stable/ussuri gate onwards for python2.7
+      coverage then you need to do override-checkout with any stable
+      branch less than or equal to stable/train.
       Former names for this job where:
         * legacy-tempest-dsvm-neutron-full
         * gate-tempest-dsvm-neutron-full-ubuntu-xenial
@@ -114,7 +118,7 @@
 
 - job:
     name: tempest-full-oslo-master
-    parent: tempest-full
+    parent: tempest-full-py3
     description: |
       Integration test using current git of oslo libs.
       This ensures that when oslo libs get released that they
@@ -142,9 +146,6 @@
       - opendev.org/openstack/oslo.utils
       - opendev.org/openstack/oslo.versionedobjects
       - opendev.org/openstack/oslo.vmware
-    vars:
-      devstack_localrc:
-        USE_PYTHON3: True
 
 - job:
     name: tempest-full-parallel
@@ -201,7 +202,7 @@
     branches: ^(?!stable/ocata).*$
     description: |
       This  job runs integration tests for networking. This is subset of
-      'tempest-full' job and run only Neutron and Nova related tests.
+      'tempest-full-py3' job and run only Neutron and Nova related tests.
       This is meant to be run on neutron gate only.
     vars:
       tox_envlist: integrated-network
@@ -222,7 +223,7 @@
     branches: ^(?!stable/ocata).*$
     description: |
       This job runs integration tests for compute. This is
-      subset of 'tempest-full' job and run Nova, Neutron, Cinder (except backup tests)
+      subset of 'tempest-full-py3' job and run Nova, Neutron, Cinder (except backup tests)
       and Glance related tests. This is meant to be run on Nova gate only.
     vars:
       tox_envlist: integrated-compute
@@ -244,7 +245,7 @@
     branches: ^(?!stable/ocata).*$
     description: |
       This job runs integration tests for placement. This is
-      subset of 'tempest-full' job and run Nova and Neutron
+      subset of 'tempest-full-py3' job and run Nova and Neutron
       related tests. This is meant to be run on Placement gate only.
     vars:
       tox_envlist: integrated-placement
@@ -265,7 +266,7 @@
     branches: ^(?!stable/ocata).*$
     description: |
       This job runs integration tests for image & block storage. This is
-      subset of 'tempest-full' job and run Cinder, Glance, Swift and Nova
+      subset of 'tempest-full-py3' job and run Cinder, Glance, Swift and Nova
       related tests. This is meant to be run on Cinder and Glance gate only.
     vars:
       tox_envlist: integrated-storage
@@ -281,7 +282,7 @@
     branches: ^(?!stable/ocata).*$
     description: |
       This job runs integration tests for object storage. This is
-      subset of 'tempest-full' job and run Swift, Cinder and Glance
+      subset of 'tempest-full-py3' job and run Swift, Cinder and Glance
       related tests. This is meant to be run on Swift gate only.
     vars:
       tox_envlist: integrated-object-storage
@@ -294,9 +295,6 @@
 - job:
     name: tempest-full-py3-ipv6
     parent: devstack-tempest-ipv6
-    # This currently works from stable/pike on.
-    # Before stable/pike, legacy version of tempest-full
-    # 'legacy-tempest-dsvm-neutron-full' run.
     branches: ^(?!stable/ocata).*$
     description: |
       Base integration test with Neutron networking, IPv6 and py3.
@@ -542,7 +540,7 @@
 
 - job:
     name: tempest-pg-full
-    parent: tempest-full
+    parent: tempest-full-py3
     description: |
       Base integration test with Neutron networking and PostgreSQL.
       Former name for this job was legacy-tempest-dsvm-neutron-pg-full.
@@ -550,7 +548,6 @@
       devstack_localrc:
         ENABLE_FILE_INJECTION: true
         DATABASE_TYPE: postgresql
-        USE_PYTHON3: True
 
 - project-template:
     name: integrated-gate-networking