DNB imports are not writing DNB id if a match is already found

[hornc]

Example re-import edit:

https://openlibrary.org/books/OL27029002M/Das_indische_Tuch?_compare=Compare&b=5&a=4&m=diff

The source MARC was added, but the more useful DNB id (DNB200004271) was not.

[hornc]

see internetarchive/openlibrary#5599 for relevant code area

[hornc]

desired metadata update e.g.:

"identifiers": {"dnb": ["810887746"]}

(from https://openlibrary.org/books/OL30393926M/%C3%84thanol_und_h%C3%B6here_Alkohole_im_Serum_von_Diabetikern )

[hornc]

Command to reimport and test https://openlibrary.org/books/OL27029002M/Das_indische_Tuch

./bulk-import.py -n 1 -o 512231530 -f dnb_all_dnbmarc_20200615-1.mrc marc_dnb_202006

After running this reimport, the record should have a DNB id of 200004271

[hornc]

Now awaiting internetarchive/openlibrary#6351 to be merged and deployed for re-test.

[hornc]

This code is currently on staging (Not yet on production), but the test has worked on staging:
https://staging.openlibrary.org/books/OL27029002M/Das_indische_Tuch?_compare=Compare&b=6&a=5&m=diff

[hornc]

see also: https://openlibrary.org/books/OL26857113M/eiszeit-4000-utopisch-technischer-roman?_compare=Compare&b=4&a=3&m=diff for a working example of re-importing OCLC and DNB identifiers.