I ran pkcon update force. I noticed PackageKit is logging about only_trusted:0. That is, an operation where the only_trusted option is disabled. Even though I did not pass --allow-untrusted to pkcon.
PackageKit[19819]: uid 1000 is trying to obtain org.freedesktop.packagekit.system-sources-refresh auth (only_trusted:0)
So PackageKit is writing a log message about allowing untrusted packages. I did not want it to do that. I did not ask it do that. Why is it logging this message? Is there a problem in PackageKit?
$ sudo systemctl status packagekit.service
● packagekit.service - PackageKit Daemon
Loaded: loaded (/usr/lib/systemd/system/packagekit.service; static; vendor preset: disabled)
Active: active (running) since Mon 2019-04-08 12:34:58 BST; 1min 29s ago
Main PID: 19819 (packagekitd)
Tasks: 3 (limit: 4915)
Memory: 192.7M
CGroup: /system.slice/packagekit.service
└─19819 /usr/libexec/packagekitd
Apr 08 12:34:58 alan-laptop PackageKit[19819]: daemon start
Apr 08 12:34:58 alan-laptop systemd[1]: Starting PackageKit Daemon...
Apr 08 12:34:58 alan-laptop systemd[1]: Started PackageKit Daemon.
Apr 08 12:34:58 alan-laptop PackageKit[19819]: uid 1000 is trying to obtain org.freedesktop.packagekit.system-sources-refresh auth (only_trusted:0)
Apr 08 12:34:58 alan-laptop PackageKit[19819]: uid 1000 obtained auth for org.freedesktop.packagekit.system-sources-refresh
Apr 08 12:35:09 alan-laptop PackageKit[19819]: refresh-cache transaction /17652_eabaebee from uid 1000 finished with success after 11018ms
$ rpm -q PackageKit
PackageKit-1.1.12-2.fc29.x86_64