ActiveRecord::RecordInvalid: Validation failed: Issue has already been linked to another vulnerability

https://sentry.gitlab.net/gitlab/gitlabcom/issues/2536096/?referrer=gitlab_plugin

ActiveRecord::RecordInvalid: Validation failed: Issue has already been linked to another vulnerability
  active_record/validations.rb:80:in `raise_validation_error'
    raise(RecordInvalid.new(self))
  active_record/validations.rb:53:in `save!'
    perform_validations(options) ? super : raise_validation_error
  active_record/transactions.rb:318:in `block in save!'
    with_transaction_returning_status { super }
  active_record/transactions.rb:375:in `block in with_transaction_returning_status'
    status = yield
  active_record/connection_adapters/abstract/database_statements.rb:278:in `transaction'
    yield
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Validation failed: Issue has already been linked to another vulnerability