If an object exists, we don't do anything. If it needs to be restored from an exported version (e.g. a Bag), it will need to be deleted first, then we can replace it.
As of 98f2bb3565f1179b429823e1514919a067f43b12 this is in place, but we have an additional problem (what if there is more than one object input directory?). We can only specify one PID on the command line.
If an object exists, we don't do anything. If it needs to be restored from an exported version (e.g. a Bag), it will need to be deleted first, then we can replace it.