Add missing test

See hbz/nwbib#66
WIP
Merge branch 'master' into issue-502-ZDB-HT-data
Point ZDB owl:sameAs link to hbz ID instead to itself

See #502
Merge pull request #595 from lobid/issue-502-ZDB-HT-data

Point ZDB owl:sameAs link to hbz ID instead to itself