Disable ipv6_subnet_attributes feature in case of contrail env

"ipv6_ra_mode" and "ipv6_address_mode" fields are not supported
by OpenContrail (at least in 4.0). Related bug:
https://bugs.launchpad.net/juniperopenstack/+bug/1604568

Change-Id: I95a4e2bd46b6d357c2474187bed9d23488be42ba
Related-PROD: PROD-22168
diff --git a/_modules/runtest/tempest_sections/network_feature_enabled.py b/_modules/runtest/tempest_sections/network_feature_enabled.py
index b608cd4..8a2d213 100644
--- a/_modules/runtest/tempest_sections/network_feature_enabled.py
+++ b/_modules/runtest/tempest_sections/network_feature_enabled.py
@@ -45,6 +45,13 @@
 
     @property
     def ipv6_subnet_attributes(self):
+        # "ipv6_ra_mode" and "ipv6_address_mode" fields are not supported
+        # by OpenContrail (at least in 4.0). Related bug:
+        # https://bugs.launchpad.net/juniperopenstack/+bug/1604568
+        contrail_enabled = conditions.BaseRule('*.opencontrail.control.enabled',
+                                               'eq', True, multiple='any')
+        if contrail_enabled.check(self.pillar):
+            return False
         return conditions.BaseRule('*.neutron.server.enabled', 'eq', True,
                                    multiple='any').check(self.pillar)