This one works even when RequestLimitExceeded errors happen.
Tests are not passing yet.
Metadata should not be in the dict form of the record
Limits PD to a single engine type for now because currently it is awkward to figure out what need to register for a particular queued process.
This exception occurs when a provisioning variable is missing. If not caught, it bubbles up all the way to the dashi handler and the instance is stuck in 100-REQUESTING state.
Dashi now depends on Kombu 2.1.2 which fixed the bug.