Comment 9 for bug 1785314

There are two ways to request a machine that isn't in a space today:

 * Use the not_space constraint to tell MAAS you don't want a particular space. (For example, you might use not_space=dmz if you'd like to request any machine except one that is in a particular space.)

 * Omit the space constraint altogether. (This is pretty much the same as saying you don't care which space a machine is in, except that you could get a machine that IS in an unwanted space. But the same is true if you say "give me a machine that has an undefined space" - it could also include interfaces that are in an unwanted space. so it's better in this case for users to be explicit about which spaces they DON'T want.)