bad root shell in /etc/passwd

[Gary Aitken]

I mistakenly changed the root shell to something which doesn't exist.
Was trying to make it bash and used /bin/bash instead of /usr/local/bin/bash.
As a consequence, all login attempts fail because the shell can't be found.

Unfortunatley, I shut down the session in which I modified /etc/passwd and
I don't have a root shell running anywhere, so I can't fix it.

I'm concerned that booting single user will have the same problem.
Or will it fall back to /bin/sh?

guidance?