Often when testing I have to create a hack which is annoying to maintain.
I think it might be handy to add a custom compile-time flag that developers can use if they want to test things locally without having to backfill a bunch of blocks.
There is probably an argument to have a feature called "backfill" which is enabled by default and can be disabled. I didn't go this route because I think it's counter-intuitive to have a feature that enables a core and necessary behaviour.
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