ironic-conductor tripleo-current image in quay fails to run

After deploying the undercloud with tripleo-quickstart with:

./quickstart.sh -R master --no-clone \
    --tags all -I -T none \
    --nodes config/nodes/1ctlr_1comp.yml \
    --extra-vars docker_registry_host="quay.io" \
    --extra-vars docker_prep_prefix="openstack-" \
    --extra-vars docker_ceph_tag="v6.0.0-stable-6.0-pacific-centos-8-x86_64" \
    --extra-vars container_build_id="current-tripleo" \
    -p quickstart-extras-undercloud.yml 127.0.0.2

ironic-conductor container fails to start, and it just keeps restarting without any error on the logs. When ironic-conductor is in this state, the next step on the tripleo-quickstart deploy (overcloud-image-prep) is unable to import the overcloud images into ironic's PXE and the step fails.

When executed with:

./quickstart.sh -R master --no-clone --tags all \
           -I --teardown none \
           --nodes config/nodes/1ctlr_1comp.yml \
           -p quickstart-extras-overcloud-prep.yml 127.0.0.2

fails at step:

openstack overcloud node import instackenv.json

with error:

Key mac is deprecated, please use ports.
Key mac is deprecated, please use ports.
Error contacting Ironic server: Resource temporarily unavailable, please retry. (HTTP 503). Attempt 6 of 6
Exception occured while running the command
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/tripleoclient/command.py", line 34, in run
    super(Command, self).run(parsed_args)
  File "/usr/lib/python3.6/site-packages/osc_lib/command/command.py", line 39, in run
    return super(Command, self).run(parsed_args)
  File "/usr/lib/python3.6/site-packages/cliff/command.py", line 185, in run
    return_code = self.take_action(parsed_args) or 0
  File "/usr/lib/python3.6/site-packages/tripleoclient/v2/overcloud_node.py", line 107, in take_action
    instance_boot_option=parsed_args.instance_boot_option
  File "/usr/lib/python3.6/site-packages/tripleoclient/workflows/baremetal.py", line 88, in register_or_update
    ramdisk_name=ramdisk_name)
  File "/usr/lib/python3.6/site-packages/tripleo_common/utils/nodes.py", line 601, in register_all_nodes
    node = _update_or_register_ironic_node(node, node_map, client=client)
  File "/usr/lib/python3.6/site-packages/tripleo_common/utils/nodes.py", line 566, in _update_or_register_ironic_node
    ironic_node = register_ironic_node(node, client)
  File "/usr/lib/python3.6/site-packages/tripleo_common/utils/nodes.py", line 441, in register_ironic_node
    ironic_node = client.node.create(**create_map)
  File "/usr/lib/python3.6/site-packages/ironicclient/common/base.py", line 339, in create
    headers=headers)
  File "/usr/lib/python3.6/site-packages/ironicclient/common/http.py", line 405, in json_request
    resp = self._http_request(url, method, **kwargs)
  File "/usr/lib/python3.6/site-packages/ironicclient/common/http.py", line 287, in wrapper
    return func(self, url, method, **kwargs)
  File "/usr/lib/python3.6/site-packages/ironicclient/common/http.py", line 387, in _http_request
    error_json.get('debuginfo'), method, url)
ironicclient.common.apiclient.exceptions.ServiceUnavailable: Resource temporarily unavailable, please retry. (HTTP 503)
Resource temporarily unavailable, please retry. (HTTP 503)