The WiredTiger compatibility tests currently run verify using one version of binary against data files generated by another version of binary. The default scenario is clean shutdown and the data files are expected to be written completely and intact. In a real world scenario databases could run into an unclean shutdown and we should add coverage for this testing gap.

The scenario to be covered:

1. WT version X starts up, runs workloads and generates data files
2. WT runs into an unclean shutdown during the workload
3. Verify WT version Y can start up with the data files generated by step 1
4. Run verify 

Note: Y could be X-1 or X+1 to cover both downgrade and upgrade cases.