Upload remapping is a bit too enthousiastic

“only” have to do a rebake… yes, on one hand I think it’s good to get rid of the hacky remaps, on the other hand it seems like the backup/restore and migrate from/to S3 processes are getting more and more complicated and hard.

See also a number of issues in Migrate_from_s3 problems which are kind of related but they’re not all covered by your proposed solution.