make operations atomic: temp dirs?

[derhuerst]

Currently, many operations in this project work inside directory within data. If they fail, make doesn't delete them (AFAIK it only does that with files), so a broken artefact is left behind. Because the subsequent operation doesn't (or can't even) check the directory's integrity, the whole pipeline produces subtly broken artefacts.

One possible solution is to make all operations atomic, by letting each

1. create a temp dir
2. work within this tmp dir, e.g. produce the artefact
3. mv the temp dir to the desired location.

Another option would be to get make to delete directories on failures.