Correctly emulate pre-fork-4 behavior to allow us to safely validate old blocks without asserting or accessing uninitialized memory.  Fixes some crashes reported, like one reported in BitShares/bitshares_toolkit#647
Correctly emulate pre-fork-4 behavior to allow us to safely validate old blocks without asserting or accessing uninitialized memory.  Fixes some crashes reported, like one reported in BitShares/bitshares_toolkit#647

bitshares/bitshares,frrp/bitshares,frrp/bitshares,bitshares/bitshares-0.x,camponez/bitshares,bitshares/devshares,camponez/bitshares,camponez/bitshares,bitshares/bitshares,frrp/bitshares,bitshares/devshares,bitshares/bitshares,camponez/bitshares,RemitaBit/Remitabit,jakeporter/Bitshares,bitshares/devshares,bitshares/bitshares-0.x,RemitaBit/Remitabit,bitshares/bitshares,bitshares/bitshares,jakeporter/Bitshares,jakeporter/Bitshares,bitshares/bitshares-0.x,bitshares/devshares,FollowMyVote/bitshares,camponez/bitshares,RemitaBit/Remitabit,bitshares/bitshares-0.x,camponez/bitshares,FollowMyVote/bitshares,jakeporter/Bitshares,RemitaBit/Remitabit,frrp/bitshares,jakeporter/Bitshares,bitshares/bitshares-0.x,Ziftr/bitshares,FollowMyVote/bitshares,RemitaBit/Remitabit,frrp/bitshares,frrp/bitshares,Ziftr/bitshares,FollowMyVote/bitshares,Ziftr/bitshares,bitshares/bitshares,jakeporter/Bitshares,RemitaBit/Remitabit,FollowMyVote/bitshares,bitshares/bitshares-0.x,FollowMyVote/bitshares,bitshares/devshares,bitshares/devshares,Ziftr/bitshares