I observed the following problem on a Leap 15.2 system (used as openQA worker):

```
martchus@openqaworker3:/srv/salt> sudo systemctl status purge-kernels.service
purge-kernels.service - Purge old kernels
   Loaded: loaded (/usr/lib/systemd/system/purge-kernels.service; enabled;
vendor preset: enabled)
   Active: failed (Result: exit-code) since Mon 2021-03-15 06:51:54 CET; 1 day
4h ago
 Main PID: 1166 (code=exited, status=7)

Mar 15 06:51:36 openqaworker3 systemd[1]: Starting Purge old kernels...
Mar 15 06:51:54 openqaworker3 zypper[1166]: System management is locked by the
application with pid 1286 (zypper).
Mar 15 06:51:54 openqaworker3 zypper[1166]: Close this application before
trying again.
Mar 15 06:51:54 openqaworker3 systemd[1]: purge-kernels.service: Main process
exited, code=exited, status=7/NOTRUNNING
Mar 15 06:51:54 openqaworker3 systemd[1]: Failed to start Purge old kernels.
Mar 15 06:51:54 openqaworker3 systemd[1]: purge-kernels.service: Unit entered
failed state.
Mar 15 06:51:54 openqaworker3 systemd[1]: purge-kernels.service: Failed with
result 'exit-code'.
```

Maybe this can be improved, e.g. by adding a retry?

Unfortunately I don't know what the conflicting process was because I only
found out about the problem when it had already terminated.

Related openQA project ticket: https://progress.opensuse.org/issues/90170