### What needs to get done [Review-tools](https://snapcraft.io/review-tools) checks and flags for snaps with [external symlinks](https://git.launchpad.net/review-tools/tree/reviewtools/reviews/sr_lint.py). Snapcraft should have a linter for this. ### Why it needs to get done Quicker development iterations. Users should be warned at build time rather than when the snap is uploaded to the store.