Comment 3 for bug 984640

OK, I see your point; in this case it would be perfectly reasonable to try to deploy to "some-named-node" that you expect to become available soon (even if it isn't right now), and preflighting would kill that possibility.

Clearer communication of machine-launch errors in status still strikes me as a good idea, though, and I'm not entirely convinced that preflighting is actually a bad idea; I think I'd rather have it and to be able to turn it off selectively than leave it out forever.

I'm also very much on the fence about interactivity. I think I'd prefer:

  $ juju deploy mysql --constraints maas-name=bob
  ERROR "bob" is in use or does not exist
  $ juju deploy mysql --constraints maas-name=bob --shut-up-i-know-what-im-doing

...and just include the --shut-up flag in scripts, rather than have interactivity by default; that way an error in a script is actually communicated as an error (as opposed to blocking on user input forever). Except, hmm, we've kinda already made the opposite choice for host-key confirmation. Bah.