Followed the plan from D14272 and restarted two Harbormaster workers at the same time.
After this patch was applied, they no longer created two different resources (we expect it to be possible for this to happen, just very hard).
We should still be able to force this race by putting something like `sleep(10)` right before the query, then `sleep(10)` right after it. That would prevent the allocators from seeing one another (so they would both think there were no other resources) and push us down the pathway where we exceed the soft limit.