Description of problem:
Overcloud deployment failed when compute nic config template without br-ex bridge
with error:
        "Error: 'ovs-vsctl --timeout=5 set Bridge br-ex other-config:mac-table-size=50000' returned 1 instead of one of [0]",
        "Error: /Stage[main]/Ovn::Controller/Exec[br-ex]/returns: change from 'notrun' to ['0'] failed: 'ovs-vsctl --timeout=5 set Bridge br-ex other-config:mac-table-size=50000' returned 1 instead of one of [0]",

Spine-Leaf network topology

Compute nic config template will be attached

Version-Release number of selected component (if applicable):
Compose: RHOS_TRUNK-15.0-RHEL-8-20190403.n.3

openstack-tripleo-common-containers-10.6.1-0.20190404000356.3398bec.el8ost.noarch
python3-tripleoclient-heat-installer-11.3.1-0.20190403170353.73cc438.el8ost.noarch
openstack-tripleo-image-elements-10.3.1-0.20190325204940.253fe88.el8ost.noarch
ansible-tripleo-ipsec-9.0.1-0.20190220162047.f60ad6c.el8ost.noarch
ansible-role-tripleo-modify-image-1.0.1-0.20190402220346.012209a.el8ost.noarch
python3-tripleoclient-11.3.1-0.20190403170353.73cc438.el8ost.noarch
python3-tripleo-common-10.6.1-0.20190404000356.3398bec.el8ost.noarch
openstack-tripleo-validations-10.3.1-0.20190403171315.a4c40f2.el8ost.noarch
openstack-tripleo-common-10.6.1-0.20190404000356.3398bec.el8ost.noarch
openstack-tripleo-puppet-elements-10.2.1-0.20190327211339.0f6cacb.el8ost.noarch
openstack-tripleo-heat-templates-10.4.1-0.20190403221322.0d98720.el8ost.noarch
puppet-tripleo-10.3.1-0.20190403180925.81d7714.el8ost.noarch


How reproducible:


Steps to Reproduce:
1. Build virt env with Spine Leaf topology 
2. Install UC
3. Start deploy Overcloud

Actual results:
PLAY [External deployment Post Deploy tasks] ***********************************

PLAY RECAP *********************************************************************
overcloud-compute0-0       : ok=135  changed=51   unreachable=0    failed=1   
overcloud-compute1-0       : ok=137  changed=63   unreachable=0    failed=1   
overcloud-compute2-0       : ok=137  changed=63   unreachable=0    failed=1   
overcloud-controller0-0    : ok=230  changed=91   unreachable=0    failed=0   
overcloud-controller0-1    : ok=219  changed=88   unreachable=0    failed=0   
overcloud-controller0-2    : ok=219  changed=88   unreachable=0    failed=0   
undercloud                 : ok=11   changed=7    unreachable=0    failed=0   

Wednesday 10 April 2019  20:37:35 +0000 (0:00:00.170)       0:35:40.920 ******* 
=============================================================================== 

Ansible failed, check log at /var/lib/mistral/overcloud/ansible.log.
Exception occured while running the command
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/tripleoclient/command.py", line 30, in run
    super(Command, self).run(parsed_args)
  File "/usr/lib/python3.6/site-packages/osc_lib/command/command.py", line 41, in run
    return super(Command, self).run(parsed_args)
  File "/usr/lib/python3.6/site-packages/cliff/command.py", line 184, in run
    return_code = self.take_action(parsed_args) or 0
  File "/usr/lib/python3.6/site-packages/tripleoclient/v1/overcloud_deploy.py", line 949, in take_action
    verbosity=self.app_args.verbose_level)
  File "/usr/lib/python3.6/site-packages/tripleoclient/workflows/deployment.py", line 327, in config_download
    raise exceptions.DeploymentError("Overcloud configuration failed.")
tripleoclient.exceptions.DeploymentError: Overcloud configuration failed.


Expected results:
Passed

Additional info: