It will be important for proper subscription testing and it doesn't hurt even
though technically we've got two http servers listening after this change (one
is a regular Server's http.Server and one is httptest's Server). Reusing
rpc.Server would be nice, but it requires some changes to Start sequence to
start Listener with net.Listen and then communicate back its resulting
Addr. It's not very convenient especially given that no other code needs it,
so doing these changes just for a bit cleaner testing seems like and
overkill.
Update config appropriately. Update Start comment along the way.
612500ed96