Reproduce:
set system login user ssh-test-user authentication public-keys vyos key 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 set system login user ssh-test-user authentication public-keys vyos type ssh-rsa
Error:
vyos@vyos# cat /etc/passwd | grep ssh sshd:x:112:65534::/run/sshd:/usr/sbin/nologin ssh_test_user:x:1003:100::/home/ssh_test_user:/bin/vbash
Found while writing a smoketest for public-key auth.