Add unit test for stacking external/loop protection (missing test coverage).
Add unit test for stacking external/loop protection (missing test coverage).

shivarammysore/faucet,gizmoguy/faucet,anarkiwi/faucet,trungdtbk/faucet,shivarammysore/faucet,gizmoguy/faucet,REANNZ/faucet,REANNZ/faucet,mwutzke/faucet,trungdtbk/faucet,faucetsdn/faucet,mwutzke/faucet,faucetsdn/faucet,anarkiwi/faucet