If --include doesn't match a machine, error out

[domenkozar]

Currently NixOps won't complain if deploy -d foo --include vm won't match even a single machine.

[domenkozar]

I've researched this a bit.

nixops/deployment.py has two functions called should_do and should_do_n that take a single machines, includes and excludes and tell if it should be used.

To actually error out if machine doesn't exist we'd have to refactor this function to take all machines and then it can error out if missing.

[RocketPuppy]

I might be able to take on implementing this. Given the last comment about implementation was years ago, should I assume it's no longer relevant?