In the most recent report, I found this error in the Mistral logs...

http://logs.openstack.org/24/608324/1/gate/tripleo-ci-centos-7-undercloud-oooq/0843431/logs/undercloud/var/log/mistral/executor.log.txt.gz#_2018-10-10_08_03_55_473

2018-10-10 08:03:55.473 26208 ERROR tripleo_common.actions.templates [req-bed99655-45c0-4455-9628-00e97accb2d7 7fff713b28d647d4bb0564dae6a00d32 c5a85f06ef4f47468d7054f618c0febd - default default] Error storing file network/service_net_map.yaml in container overcloud: ClientException: put_object(u'overcloud', u'network/service_net_map.yaml', ...) failure and no ability to reset contents for reupload.
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates [req-bed99655-45c0-4455-9628-00e97accb2d7 7fff713b28d647d4bb0564dae6a00d32 c5a85f06ef4f47468d7054f618c0febd - default default] Error occurred while processing custom roles.: Exception: Error storing file network/service_net_map.yaml in container overcloud
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates Traceback (most recent call last):
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates   File "/usr/lib/python2.7/site-packages/tripleo_common/actions/templates.py", line 368, in run
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates     self._process_custom_roles(context)
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates   File "/usr/lib/python2.7/site-packages/tripleo_common/actions/templates.py", line 346, in _process_custom_roles
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates     context=context)
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates   File "/usr/lib/python2.7/site-packages/tripleo_common/actions/templates.py", line 157, in _j2_render_and_put
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates     raise Exception(error_msg)
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates Exception: Error storing file network/service_net_map.yaml in container overcloud
2018-10-10 08:03:55.474 26208 ERROR tripleo_common.actions.templates 

It looks like the upload to swift failed, but this code isn't written to retry on failure. Looking at the swift logs it happened due to a timeout.

http://logs.openstack.org/24/608324/1/gate/tripleo-ci-centos-7-undercloud-oooq/0843431/logs/undercloud/var/log/swift/swift.log.txt.gz#_Oct_10_08_03_52

Oct 10 08:03:52 centos-7-inap-mtl01-0002810891 proxy-server: ERROR with Object server 192.168.24.1:6000/1 re: Trying to get final status of PUT to /v1/AUTH_c5a85f06ef4f47468d7054f618c0febd/overcloud/network/service_net_map.yaml: Timeout (60.0s) (txn: tx4931d10773dc4044b0baf-005bbdb22c)
Oct 10 08:03:52 centos-7-inap-mtl01-0002810891 proxy-server: Object PUT returning 503 for [503] (txn: tx4931d10773dc4044b0baf-005bbdb22c) (client_ip: 192.168.24.1)
Oct 10 08:03:52 centos-7-inap-mtl01-0002810891 proxy-server: 192.168.24.1 192.168.24.1 10/Oct/2018/08/03/52 PUT /v1/AUTH_c5a85f06ef4f47468d7054f618c0febd/overcloud/network/service_net_map.yaml HTTP/1.0 503 - python-swiftclient-3.5.0 gAAAAABbvbHJ-yJb... 6147 118 - tx4931d10773dc4044b0baf-005bbdb22c - 60.0126 - - 1539158572.454325914 1539158632.466906071 0