The .cvmfscatalog marker files that can be created by cvmfs_server ingest sometimes have content but a length of zero in the meta-data. They are therefore unreadable.
This requires three fixes:
- Ensure .cvmfscatalog markers are indeed empty
- Cross check actual size with meta-data size on publish and on download to provide early and accurate failure reporting in case a similar problem appears in the future
- Fix-up existing .cvmfscatalog marker files in unpacked.cern.ch