Createrepo *sometimes* creates an empty 'garbageid' directory. This directory is not removed after createrepo finishes. Unfortunately I have no idea how to reproduce it. Wouldn't be possible to create it under /tmp (tempfile.mkdtemp() etc.) instead of under outputdir?
Actually, createrepo-0.9.9-6.fc17.noarch creates 'garbageid' dir on `createrepo --update .` - it is always reproducible.
*** This bug has been marked as a duplicate of bug 728584 ***