to avoid implicitly creating a variant during a GET to a read replica,
which will raise an exception and cause the image to fail to load.
This feels pretty brittle, to be honest, and we'll need to be careful
in the future about creating and using new variants; we will probably
need to backfill the new variant for existing images because we can't
guarantee that they will be created implicitly/lazily if the GET lands
on the replica.
ref: https://fizzy.37signals.com/5986089/collections/7/cards/942
Mike Dalessio
ef6198d394