Snapcraft notifies that steps will be skipped for parts that aren't in command

[Kyle Fazzari]

Let's say I have two independent parts: part1 and part2. I run `snapcraft prime part1` and snapcraft prints the following:

Preparing to pull part1
Pulling part1
Preparing to build part1
Building part1
Staging part1
Priming part1

This is as expected. I then run `snapcraft prime part2` and expect the exact same output for part2, but I actually get this:

Skipping pull part1 (already ran)
Skipping build part1 (already ran)
Skipping stage part1 (already ran)
Skipping prime part1 (already ran)
Preparing to pull part2
Pulling part2
Preparing to build part2
Building part2
Staging part2
Priming part2

There's a lot of noise there about part1 when I didn't request anything about part1.