if nothing to build, do not push

[deitch]

Signed-off-by: Avi Deitcher avi@deitcher.net

- What I did

With the earlier PR #3863 , for pkg build, if the image exists in the remote registry we don't bother pulling it unless they explicitly requested --pull. This is much more efficient.

However, this might break pkg push in the following scenario:

1. lkt pkg push pkg/foo
2. The image is not in cache at all, but is entirely in registry
3. Nothing gets built (correctly), nothing gets pulled (correctly)
4. It now tries to push from cache and finds nothing there.
5. This fixes it so that it does not try to push if it did not build anything or find anything local

- How I did it

Added logic to check if we built anything or found anything locally.

I would add that there might be a cleaner way to do this, specifically just check before pushing, "do we have anything in cache". The net result, though, is the same.

- How to verify it

CI

- Description for the changelog

Handle pkg push when nothing is built or pulled.

[giggsoff]

It solves the problems in CI of EVE-OS (at least on my fork with updated linuxkit and removal of additional pull steps before push).