Fix pep8 errors

pylint 2.7.0 added additional checks for inconsistent-return-statements:
- inconsistent-return-statements message is now emitted if one of
  try/except statement is not returning explicitly while the other do.

Change-Id: I196e13996ce4bce93d9a8eed87f6c3cb8ef3cea1

octavia/api/v2/controllers/listener.py

@@ -330,6 +330,7 @@ class ListenersController(base.BaseController):
         except odb_exceptions.DBError as e:
             raise exceptions.InvalidOption(value=listener_dict.get('protocol'),
                                            option='protocol') from e
+        return None
 
     @wsme_pecan.wsexpose(listener_types.ListenerRootResponse,
                          body=listener_types.ListenerRootPOST, status_code=201)

octavia/api/v2/controllers/member.py

@@ -134,6 +134,7 @@ class MemberController(base.BaseController):
             # before creation or update since the exception messages
             # do not give any information as to what constraint failed
             raise exceptions.InvalidOption(value='', option='') from e
+        return None
 
     def _validate_pool_id(self, member_id, db_member_pool_id):
         if db_member_pool_id != self.pool_id:

octavia/certificates/manager/barbican.py

@@ -91,6 +91,7 @@ class BarbicanCertManager(cert_mgr.CertManager):
         except Exception as e:
             with excutils.save_and_reraise_exception():
                 LOG.error('Error storing certificate data: %s', str(e))
+        return None
 
     def get_cert(self, context, cert_ref, resource_ref=None, check_only=False,
                  service_name=None):

octavia/certificates/manager/barbican_legacy.py

@@ -114,6 +114,7 @@ class BarbicanCertManager(cert_mgr.CertManager):
                                     i.name, old_ref)
             with excutils.save_and_reraise_exception():
                 LOG.error('Error storing certificate data: %s', str(e))
+        return None
 
     def get_cert(self, context, cert_ref, resource_ref=None, check_only=False,
                  service_name=None):
@@ -158,6 +159,7 @@ class BarbicanCertManager(cert_mgr.CertManager):
         except Exception as e:
             with excutils.save_and_reraise_exception():
                 LOG.error('Error getting cert %s: %s', cert_ref, str(e))
+        return None
 
     def delete_cert(self, context, cert_ref, resource_ref, service_name=None):
         """Deregister as a consumer for the specified cert.

octavia/common/policy.py

@@ -118,6 +118,7 @@ class Policy(oslo_policy.Enforcer):
                 LOG.debug('Policy check for %(action)s failed with '
                           'credentials %(credentials)s',
                           {'action': action, 'credentials': credentials})
+        return None
 
     def check_is_admin(self, context):
         """Does roles contains 'admin' role according to policy setting.

octavia/common/utils.py

@@ -189,4 +189,5 @@ class exception_logger(object):
             except Exception as e:
                 with excutils.save_and_reraise_exception():
                     self.logger(e)
+            return None
         return call

octavia/controller/worker/task_utils.py

@@ -264,3 +264,4 @@ class TaskUtils(object):
             LOG.error("Failed to get loadbalancer %(loadbalancer)s "
                       "due to: %(except)s",
                       {'loadbalancer': loadbalancer_id, 'except': str(e)})
+        return None

octavia/controller/worker/v1/controller_worker.py

@@ -111,6 +111,7 @@ class ControllerWorker(base_taskflow.BaseTaskFlowEngine):
             return create_amp_tf.storage.fetch('amphora')
         except Exception as e:
             LOG.error('Failed to create an amphora due to: %s', str(e))
+        return None
 
     def delete_amphora(self, amphora_id):
         """Deletes an existing Amphora.