btc-wallet: fix issue with block info requests
=/ gap (sub block block.btc-state)
=? blocks (gth gap 1)
(gulf +(block.btc-state) (dec block))
- =? blocks ?|(?=(~ blockhash) ?=(~ blockfilter))
+ =? blocks ?&((gth gap 0) ?|(?=(~ blockhash) ?=(~ blockfilter)))
(snoc blocks block)
=? blocks (gth gap 50) ~
:_ %_ state
