Cache for “updates” cannot be synchronized in f26 to f27 offline upgrade

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I ran dnf system-upgrade download --releasever=27 --allowerasing --refresh and then later on dnf systen-upgrade reboot. It then reboots, but it fails reproducible with the following:

Nov 16 14:22:15 martin-friese systemd[1]: Reached target System Initialization.
Nov 16 14:22:15 martin-friese systemd[1]: Starting System Upgrade using DNF...
Nov 16 14:22:15 martin-friese systemd[1]: Started Updates device firmware whilst offline.
Nov 16 14:22:15 martin-friese audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=fwupd-offline-update comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Nov 16 14:22:15 martin-friese systemd[1]: Listening on D-Bus System Message Bus Socket.
Nov 16 14:22:15 martin-friese systemd[1]: Starting Update the operating system whilst offline...
Nov 16 14:22:15 martin-friese pk-offline-update[1022]: another framework set up the trigger
Nov 16 14:22:15 martin-friese systemd[1]: Started Update the operating system whilst offline.
Nov 16 14:22:15 martin-friese audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=packagekit-offline-update comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Nov 16 14:22:15 martin-friese audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=packagekit-offline-update comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Nov 16 14:22:15 martin-friese audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=fwupd-offline-update comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Nov 16 14:22:17 martin-friese systemd[1]: Received SIGRTMIN+20 from PID 387 (plymouthd).
Nov 16 14:22:19 martin-friese audit[1]: SERVICE_STOP pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=systemd-rfkill comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Nov 16 14:22:19 martin-friese kernel: kauditd_printk_skb: 70 callbacks suppressed
Nov 16 14:22:19 martin-friese kernel: audit: type=1131 audit(1510838539.176:94): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=systemd-rfkill comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
Nov 16 14:22:23 martin-friese dnf[1020]: Fehler: Zwischenspeicher für Paketquelle »updates« konnte nicht synchronisiert werden
Nov 16 14:22:23 martin-friese systemd[1]: dnf-system-upgrade.service: Main process exited, code=exited, status=1/FAILURE
Nov 16 14:22:23 martin-friese systemd[1]: Failed to start System Upgrade using DNF.
Nov 16 14:22:23 martin-friese audit[1]: SERVICE_START pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='unit=dnf-system-upgrade comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=failed'
Nov 16 14:22:23 martin-friese systemd[1]: dnf-system-upgrade.service: Unit entered failed state.
Nov 16 14:22:23 martin-friese systemd[1]: dnf-system-upgrade.service: Failed with result 'exit-code'.
Nov 16 14:22:23 martin-friese systemd[1 ...