When we make the CHECKSUM file for the entire iso directory we need to name it correctly
take https://kojipkgs.fedoraproject.org/compose/rawhide/Fedora-24-20151202.n.0/compose/Server/i386/iso/
the CHECKSUM should be named Fedora-Server-24-20151202.n.0-CHECKSUM not CHECKSUM
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/pungi/pungi/issues/78
Please continue any further discussion there.