We were previously having an issue where the tutorial could
be pre-empted if you got a few messages while you were first
logging in.
I have some reservations about this being slightly fragile, and a
better approach might be to just have a bit that we use to determine
whether or not you've already seen a tutorial. (Or potentially that
checks whether or not you've ever sent a message.)
(imported from commit f8858f64a36bcd25887b76314caff283929f340c)