We want to copy the contents of a directory to another, the correct
syntax for that is `cp -a src/. dst`. I was not aware of this beauty,
so the previous patch simulated the functionality in python code.
Signed-off-by: Tom Gundersen <teg@jklm.no>
In the simplest case we don't need to make an image, a filesystem tree
will do. Also support using such a tree as input for further pipelines
through the untree stage.
Signed-off-by: Tom Gundersen <teg@jklm.no>
