Deleting a PRS is not possible if create fails for some reason

If there is some error on the PRS create and it fails, then rollback and any further attempts in deleting it fails.

2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager Traceback (most recent call last):
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager File "/usr/lib/python2.7/site-packages/gbpservice/neutron/services/grouppolicy/policy_driver_manager.py", line 119, in _call_on_drivers
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager getattr(driver.obj, method_name)(context)
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager File "/usr/lib/python2.7/site-packages/neutron/common/log.py", line 34, in wrapper
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager return method(*args, **kwargs)
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager File "/usr/lib/python2.7/site-packages/gbpservice/neutron/services/grouppolicy/drivers/resource_mapping.py", line 1209, in delete_policy_rule_set_precommit
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager context._plugin_context.session, context.current['id'])
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager File "/usr/lib/python2.7/site-packages/gbpservice/neutron/services/grouppolicy/drivers/resource_mapping.py", line 2348, in _get_policy_rule_set_sg_mapping
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager filter_by(policy_rule_set_id=policy_rule_set_id).one())
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager File "/usr/lib64/python2.7/site-packages/sqlalchemy/orm/query.py", line 2375, in one
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager raise orm_exc.NoResultFound("No row was found for one()")
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager NoResultFound: No row was found for one()
2015-09-25 16:19:52.164 10989 TRACE gbpservice.neutron.services.grouppolicy.policy_driver_manager
2015-09-25 16:19:52.167 10989 ERROR root [-] Original exception being dropped: ['Traceback (most recent call last):\n', ' File "/usr/lib/python2.7/site-packages/gbpservice/neutron/services/grouppolicy/plugin.py", line 1194, in create_policy_rule_set\n policy_context)\n', ' File "/usr/lib/python2.7/site-packages/gbpservice/neutron/services/grouppolicy/policy_driver_manager.py", line 299, in create_policy_rule_set_postcommit\n self._call_on_drivers("create_policy_rule_set_postcommit", context)\n', ' File "/usr/lib/python2.7/site-packages/gbpservice/neutron/services/grouppolicy/policy_driver_manager.py", line 134, in _call_on_drivers\n method=method_name\n', 'GroupPolicyDriverError: create_policy_rule_set_postcommit failed.\n']
2015-09-25 16:19:52.167 10989 ERROR neutron.api.v2.resource [-] create failed