Comment 1 for bug 1843413

Actual error is probably just before:
2019-09-09 17:48:01.673718 | LOOP [configure-mirrors : Update dnf cache]
2019-09-09 17:48:03.555741 | controller | 18 files removed
2019-09-09 17:48:03.556494 | controller | ok: Item: dnf clean all Runtime: 0:00:00.981399
2019-09-09 17:48:04.681273 | controller | Error: Failed to synchronize cache for repo 'updates'
2019-09-09 17:48:04.681584 | controller | ok: Item: dnf makecache Result: 1

As mentioned by Slawek, "latest" fedora still points to F28:
https://opendev.org/openstack/devstack/src/commit/650769a3115704aa8af8b346a57838d46b87ba6a/.zuul.yaml#L52