What is hanging systemctl?

[Tom Horsley]

I'm trying to do a "dnf update". The NIS server happens to be
down. Every update that attempts to do anything with cron
via systemctl seems to hang. Is there some sort of strange
connection between cron and NIS?

For instance, here is the current hang:

30203 pts/0    S+     2:33              \_ /usr/bin/python -OO /usr/bin/dnf update
19394 pts/0    S+     0:00                  \_ /bin/sh /var/tmp/rpm-tmp.eMR7ER 1 4
19395 pts/0    S+     0:00                      \_ /bin/systemctl try-restart crond.service

As near as I can tell, that try-restart will sit there
forever. Earlier, the google-chrome update tried to make
sure atd was running, and it also hung till I killed the
command.