Fix moving files from tmp dir to final location

There is something still making me un-easy about this. I think there needs to be some more tests to support it. Specifically I think I would like to see two more tests that closely match the ingest `commitWith` block mapping files to multiple fixed directories, one test where the target directories existing and one test where they don't exist, and make sure they behave in the same way.

My concern is that, as I read it, the ingest block doesn't match the comment against `commitWith` because `target` and `errors` are the parent. So I suspect that those two tests I suggest above will demonstrate that there is still room for inconsistency.