Read task tombstones from Celery database back-end, if configured

I'm using a database back-end for Celery so that I can have task tombstones for failure recovery purposes. I like Flower's default behavior of showing tasks that executed while it was running, but it's a bit misleading in my case since my Celery configuration establishes an expectation that a durable/all-inclusive store of task tombstones is available and visible in Flower. Experimenting with Flower's persistent setting shows that it appears to be saving its own history to file -- duplicating data stored in my database back-end, and still maybe missing some tasks if Flower was down at any point when tasks were processed.

I can see how the file-based store is an advantage for Flower users who don't use/want a Celery database back-end, but ideally the database back-end should be used when it's configured. A nice future add-on might be to manage the database store via Flower (e.g. to delete task tombstones of a certain age).