If input directory is wrong, foliage produces unexpected output

[andreabedini]

E.g. unexpected as in "the user doesn't expect this". The fact is that foliage is happy when it cannot find any packages. I believe this should be reported as an error instead.

[michaelpj]

I think it might also produce an invalid tar file, I can't remember. Something else broke, it wasn't just that the repository was empty.