This was a holdover from Signal's origins as a pure SMS app.
It causes problems, depends on undefined device specific behavior,
and should no longer be necessary now that we have all the
information we need to E164 all numbers.
// FREEBIE
1) Prefetch identity keys when possible
2) Always accept prefetched keys or keys from incoming messages
3) Block sending only if it's a recent change, or if always
block is enabled
// FREEBIE