I somehow don't understand why there should be anything like
"unused
source files". Why is something like this even possible?
1. Grab a package
2. Edit the spec file in a way that changes which sources are used (say, update to a new
version)
3. Do not run "fedpkg new-sources" to upload the new tarballs
4. The "sources" file now lists files that are not actually used by the spec
5. Run "fedpkg mockbuild"
6. Mockbuild attempts to download package sources
A.FI.