extracting upstream source.

[Peter Green]

As part of my dgit based autoforwardporter I want to add a script that will de-fuzz patches with fuzz and remove patches that cannot be applied.

To do this I need the "upstream" source tree. However the process of extracting the upstream source is quite fiddly, there may be multiple tarballs to deal with, tarballs may or may not have a top-level directory that needs to be removed from the paths etc.

Both dpkg-source ("commit" and "build")and dgit (quilt fixup) clearly extract the upstream source tree as part of their processing, so the code to do it already exists but i'm not sure if there is a convenient way to access it.

Any hints?