The barrier guards for ServerSideUrlRedirect were lost when it was ported to ConfigSig, and the aforementioned spurious alert was a result of that.
The query had two guards: a proper barrier guard and a heuristic one for functions named 'isLocalURL'. We should move away from the heuristic name-based sanitiser guards, so I'm only reinstating the proper barrier guard.
Therefore updating the test to test the real barrier guard.