When an orchestration step raises, salt returns the full traceback as the
step comment, and the drainer wrote it verbatim, putting ~70 lines into
so-push-drainer.log per failure. Collapse comments to one line and, for
tracebacks, keep only the lead-in and the raised exception, e.g.
"apply_soc_1: An exception occurred in this state:
salt.exceptions.AuthenticationError: Authentication error occurred."
Seen on a standalone when a pushed highstate restarted salt-master while
two queued pushes were waiting: their orchestrations lost the master
connection and failed with AuthenticationError, although the minion
completed both state runs.