the commented-out code relates to a speculative feature
that stores ALL KernelMessages in the tester so that tests can
access & assert against more than just whatever Response
they receive
e.g. if a test Request kicks off a chain of 10 Messages,
a test might grab those 10 & assert against some subset of
them; this is not possible unless we store all KernelMessages
somewhere & make them queryable
this is a speculative feature in that we don't have a specific
usecase in mind for it; it was commented-out for this reason
and because it led to significant performance issues (noticeable
slowdown of nodes)
