Do not overwrite existing hbzIds with mapped ones from maps/hbzId2zdbId.tsv.gz

[TobiasNx]

Hinted here: https://metadaten.community/t/fehlende-verlinkung-zu-ueberordnungen/511/5

While there seems to be a underlying problem with duplicates that were inherited from ALEPH.

We should not overwrite existing hbz ids.

[TobiasNx]

Context:

There are old aleph zdb records that have zdb id informations
in their MAB data in 026-1 but not in 025z1.

Due to this in context of the migration to ALMA their HT number was not replaced by the ZDB ID. Also in the old aleph lobid mapping these records had no zdbId

e.g. see:
ALEPH: http://lobid.org/hbz01/HT019286510 // https://aleph.lobid.org/resources/HT018628300
ALMA: https://lobid.org/marcxml/990217879290206441 // https://lobid.org/resources/990217879290206441

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To ensure that old links still work we added an enrichment of all records with zdbId that are part of the NZ based on the latest data from aleph data before the switch to ALMA as master.

Also we with ALMA we started to catch the ZDB ID from 035 not only when they have the prefix (DE-600) but also if (DE-599)ZDB.

This resulted in overwriting existing hbzId in the records with mapped ones. We want to adjust this mechanism so that only records WITHOUT zdbIdare enriched with their old hbzId

[TobiasNx]

The issue seems to be solved.

I had an email exchange with N.D. from Verbundgruppe: She told me that DE-599 is no indicator for a ZDB. Since only DE-600 provides the ZDB info, that it is the true copy from the ZDB.

The records that seem to be ZDB entries but have no ZDB (DE-600) id in 035 are a hbz specific copy of the ZDB entry("dublette Verbundaufnahme" ) for Monographical Series. There seems to be some kind of agreement that for monographical series the Verbund or its members have to create a duplcate record and not use the ZDB record.