Now that systemd kills processes on logout, and session timeout is required by security policies in many workplaces including mine, I fear we'll have more of those. I certainly had update sessions that involved hundreds of packages and took longer than the session timeout, whcih is often on ther order of several minutes.
How hard would it be to make dnf do the rpm transaction inside a proper system-level service (transient or otherwise)? This would greatly increase robustness against desktop crashes, ssh connection loss, KillUserProcs, and other damaging goofs.
I once hosed a RHEL5 system when an ssh terminal running yum died. Sigh.