Invalid DOIs from Pubmed import

When importing from PubMed/MEDLINE, I trusted that listed DOIs would be valid and registered. This may not have been a good idea! Consider these release entities:

https://fatcat.wiki/release/search?q=Failure+to+use+ECT+in+treatment+of+catatonia

https://fatcat.wiki/release/geyxegazqvdfzinxpk6oafx7ju
https://fatcat.wiki/release/66jfjjdlc5alvjy2onwuk4c7fq
https://fatcat.wiki/release/4iuwwkpylnfdlies3hal2shpsm
https://fatcat.wiki/release/5nlwujzn7na4hmx3eg2xhiq4vq

There seem to be two actual letters written, in the same journal issue on partially overlapping pages by different authors. There are valid PMIDs and DOIs for both, but the MEDLINE entries both have incorrect (invalid) DOIs linked, so we end up with pairs of fatcat releases with (PMID, bad DOI) and (good DOI).

Start by reproducing the PubMed/MEDLINE import using the linked Fatcat release examples and compare their PMIDs and DOIs with the source records. Done means invalid MEDLINE DOIs are not trusted, and the affected letters no longer produce duplicate releases with bad and good DOI variants.

Written by the indexing model from the issue text.