Improve incremental caching tests
Review Request #3034 - Created Oct. 24, 2015 and submitted
While attempting to capture the failure I was seeing yesterday, I made
test_task.pyway more complicated than it needs to be. But the reason I was having trouble reproducing it was that it was exactly the existing ABA case that Nick asked for a test for. But because the test wasn't inspecting the
previous_results_dir, it wasn't noticing that it wasn't being set.
- Revert test changes from r/3028
- Test the existence of the