At the moment, we don't handle lists being passed to memoized functions.
<rdar://problem/70020109>
Created attachment 410714 [details] Patch
Discussed this with Dean and Dewei, this case is a bit of a weird one because it handles what happens when someone passes a mutable argument to a memoized function. We're going to mark this as invalid and move on, the code change does what it says it does, it's just not obvious that behavior is more correct than the exception Python will raise.