diff --git a/.zuul.yaml b/.zuul.yaml
index edaa959..2bec8c4 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -279,8 +279,6 @@
 - job:
     name: tempest-slow
     parent: tempest-multinode-full
-    branches:
-      - master
     description: |
       This multinode integration job will run all the tests tagged as slow.
       It enables the lvm multibackend setup to cover few scenario tests.
diff --git a/tempest/api/compute/servers/test_device_tagging.py b/tempest/api/compute/servers/test_device_tagging.py
index d40f937..e817587 100644
--- a/tempest/api/compute/servers/test_device_tagging.py
+++ b/tempest/api/compute/servers/test_device_tagging.py
@@ -12,9 +12,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import json
-
 from oslo_log import log as logging
+from oslo_serialization import jsonutils as json
 
 from tempest.api.compute import base
 from tempest.common import utils
diff --git a/tempest/api/network/admin/test_l3_agent_scheduler.py b/tempest/api/network/admin/test_l3_agent_scheduler.py
deleted file mode 100644
index 033bf55..0000000
--- a/tempest/api/network/admin/test_l3_agent_scheduler.py
+++ /dev/null
@@ -1,83 +0,0 @@
-# Copyright 2013 IBM Corp.
-#
-#    Licensed under the Apache License, Version 2.0 (the "License"); you may
-#    not use this file except in compliance with the License. You may obtain
-#    a copy of the License at
-#
-#         http://www.apache.org/licenses/LICENSE-2.0
-#
-#    Unless required by applicable law or agreed to in writing, software
-#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-#    License for the specific language governing permissions and limitations
-#    under the License.
-
-from tempest.api.network import base
-from tempest.common import utils
-from tempest.lib import decorators
-from tempest.lib import exceptions
-
-AGENT_TYPE = 'L3 agent'
-AGENT_MODES = (
-    'legacy',
-    'dvr_snat'
-)
-
-
-class L3AgentSchedulerTestJSON(base.BaseAdminNetworkTest):
-    """Tests the following operations in the Neutron API:
-
-        List routers that the given L3 agent is hosting.
-        List L3 agents hosting the given router.
-        Add and Remove Router to L3 agent
-
-    v2.0 of the Neutron API is assumed.
-
-    The l3_agent_scheduler extension is required for these tests.
-    """
-
-    @classmethod
-    def skip_checks(cls):
-        super(L3AgentSchedulerTestJSON, cls).skip_checks()
-        if not utils.is_extension_enabled('l3_agent_scheduler', 'network'):
-            msg = "L3 Agent Scheduler Extension not enabled."
-            raise cls.skipException(msg)
-
-    @classmethod
-    def resource_setup(cls):
-        super(L3AgentSchedulerTestJSON, cls).resource_setup()
-        agents = cls.admin_agents_client.list_agents(
-            agent_type=AGENT_TYPE)['agents']
-        for agent in agents:
-            if (agent['configurations']['agent_mode'] in AGENT_MODES and
-                agent['alive']):
-                cls.agent = agent
-                break
-        else:
-            msg = "L3 Agent Scheduler enabled in conf, but L3 Agent not found"
-            raise exceptions.InvalidConfiguration(msg)
-        cls.router = cls.create_router()
-
-    @decorators.idempotent_id('b7ce6e89-e837-4ded-9b78-9ed3c9c6a45a')
-    def test_list_routers_on_l3_agent(self):
-        self.admin_agents_client.list_routers_on_l3_agent(self.agent['id'])
-
-    @decorators.idempotent_id('9464e5e7-8625-49c3-8fd1-89c52be59d66')
-    def test_add_list_remove_router_on_l3_agent(self):
-        l3_agent_ids = list()
-        self.admin_agents_client.create_router_on_l3_agent(
-            self.agent['id'],
-            router_id=self.router['id'])
-        body = (
-            self.admin_routers_client.list_l3_agents_hosting_router(
-                self.router['id']))
-        for agent in body['agents']:
-            l3_agent_ids.append(agent['id'])
-            self.assertIn('agent_type', agent)
-            self.assertEqual('L3 agent', agent['agent_type'])
-        self.assertIn(self.agent['id'], l3_agent_ids)
-        body = self.admin_agents_client.delete_router_from_l3_agent(
-            self.agent['id'],
-            self.router['id'])
-        # NOTE(afazekas): The deletion not asserted, because neutron
-        # is not forbidden to reschedule the router to the same agent
diff --git a/tempest/cmd/run.py b/tempest/cmd/run.py
index a8ef08c..823ed11 100644
--- a/tempest/cmd/run.py
+++ b/tempest/cmd/run.py
@@ -252,7 +252,7 @@
                             default=False)
         # execution args
         parser.add_argument('--concurrency', '-w',
-                            type=int,
+                            type=int, default=0,
                             help="The number of workers to use, defaults to "
                                  "the number of cpus")
         parallel = parser.add_mutually_exclusive_group()
diff --git a/tempest/cmd/subunit_describe_calls.py b/tempest/cmd/subunit_describe_calls.py
index 8dcf575..081fa7a 100644
--- a/tempest/cmd/subunit_describe_calls.py
+++ b/tempest/cmd/subunit_describe_calls.py
@@ -78,11 +78,11 @@
 import argparse
 import collections
 import io
-import json
 import os
 import re
 import sys
 
+from oslo_serialization import jsonutils as json
 import subunit
 import testtools
 
diff --git a/tempest/scenario/test_server_basic_ops.py b/tempest/scenario/test_server_basic_ops.py
index 1671216..02bc692 100644
--- a/tempest/scenario/test_server_basic_ops.py
+++ b/tempest/scenario/test_server_basic_ops.py
@@ -13,7 +13,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import json
+from oslo_serialization import jsonutils as json
 
 from tempest.common import utils
 from tempest.common import waiters
diff --git a/tempest/scenario/test_volume_boot_pattern.py b/tempest/scenario/test_volume_boot_pattern.py
index 3bc5b0b..e5730e7c 100644
--- a/tempest/scenario/test_volume_boot_pattern.py
+++ b/tempest/scenario/test_volume_boot_pattern.py
@@ -11,7 +11,7 @@
 #    under the License.
 
 from oslo_log import log as logging
-from oslo_serialization import jsonutils
+from oslo_serialization import jsonutils as json
 import testtools
 
 from tempest.common import utils
@@ -265,7 +265,7 @@
         bdms = image.get('block_device_mapping')
         if not bdms:
             bdms = image['properties']['block_device_mapping']
-        bdms = jsonutils.loads(bdms)
+        bdms = json.loads(bdms)
         snapshot_id = bdms[0]['snapshot_id']
         self._delete_snapshot(snapshot_id)
 
diff --git a/tempest/tests/lib/common/test_rest_client.py b/tempest/tests/lib/common/test_rest_client.py
index 4c0bb57..b861582 100644
--- a/tempest/tests/lib/common/test_rest_client.py
+++ b/tempest/tests/lib/common/test_rest_client.py
@@ -13,10 +13,10 @@
 #    under the License.
 
 import copy
-import json
 
 import fixtures
 import jsonschema
+from oslo_serialization import jsonutils as json
 import six
 
 from tempest.lib.common import http
diff --git a/tempest/tests/lib/services/identity/v2/test_token_client.py b/tempest/tests/lib/services/identity/v2/test_token_client.py
index dfce9b3..a592ada 100644
--- a/tempest/tests/lib/services/identity/v2/test_token_client.py
+++ b/tempest/tests/lib/services/identity/v2/test_token_client.py
@@ -12,9 +12,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import json
-
 import mock
+from oslo_serialization import jsonutils as json
 
 from tempest.lib.common import rest_client
 from tempest.lib import exceptions
diff --git a/tempest/tests/lib/services/identity/v3/test_token_client.py b/tempest/tests/lib/services/identity/v3/test_token_client.py
index 38e8c4a..a9c58df 100644
--- a/tempest/tests/lib/services/identity/v3/test_token_client.py
+++ b/tempest/tests/lib/services/identity/v3/test_token_client.py
@@ -12,9 +12,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import json
-
 import mock
+from oslo_serialization import jsonutils as json
 
 from tempest.lib.common import rest_client
 from tempest.lib import exceptions