Gerrit accounts were recently migrated to a new storage mechanism called notedb which stores data directly in git. When attempting to resolve T197083 I manually checked out the external-ids ref from the All-Users database in gerrit. I then made a commit to remove a duplicate email id from the external-ids ref. When attempting to push my change back to gerrit, my push was rejected due to many validation errors.
Apparently the migration created a notedb with a lot of invalid duplicate email records and resolving the issue will require a ton of disambiguation of the date.
I received a total of 283 errors, most of them are duplicate email errors resembling the following pattern:
remote: error: Email 'email@example.com' is not unique, it's used by the following external IDs: 'gerrit:user', 'mailto:firstname.lastname@example.org'