This doesn't seem terribly resistant to collisions. In the case of this pull request, it would require someone running the same command multiple times in the crontab of the user running Puppet (usually `root`). However, #2136 looks to expand purging beyond a single crontab --- which increases the likelihood of a collision.

Any thoughts on a more general title hash? Perhaps target crontab + command or a value from an increasing sequence would work.