apply: Unavailable Faults should indicate “why” they are unavailable

Current situation:

Random guy runs an apply, doesn’t pay close attention. The program exits cleanly and says: “Success.” But “something” still doesn’t work. Guy complains.

What he didn’t realize: One item (out of a few hundred) was skipped, because a Fault was unavailable. It’s even worse when an item uses several Faults.

Maybe we should provide a way to make it more obvious what’s going on here. Which Fault was unavailable and why?

That would be especially helpful when using bw items. I just tried debugging an error, so i called bw items -f my-node file:/some/file/with/fault/unavailable. Even bw items did not show me any errors apart from Fault Unavailable.