Sure would be nice if ... the log-parser would have a MARK keyword in addition to ERROR, WARNING, and INFO.
My thought is that the MARK keyword would transfer a significant message into the
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for the job. That way every build that fails with something like /SVNException: svn: Unknown error/ could be flagged. Sure would help track down instabilities with jobs or with Jenkins.
For added bonus points, you could also add a RESTART_BUILD keyword that would also cause the build to be retried/restarted. That's what I manually do with the unknown SVN errors.

Just a thought. By the way, the log-parser is the greatest thing since sliced bread.
-John