Last week a problem cropped up with the WT-5927 branch that wasn't exposed by regular testing. It was linked to shutdown/restart, and test_checkpoint found it readily, but only when configured to do more runs per test. (It shuts down but does not wipe the database between runs.)

All the existing test_checkpoint cases in make check do only two runs (except for the ones that only do one) so I would like to add a couple more that do more runs and fewer ops per run.