SN-2487 已核对来源，附原文与上下文。
SVN rev 139 会在加载后对区块链做一次基本检查。
SVN rev 139 does a basic check of the block chain after loading.
有了它，我们本不需要删 blk*.dat，它会自动重组回分叉点。当时没时间把这个功能做扎实。
With this we wouldn't have needed to delete blk*.dat, it would have automatically done a reorg back to the fork. There wasn't time to do a careful implementation of this at the time.
它可能比我们想要的慢，因为要把所有区块都加载一遍。如果太慢，可以让它只回溯到某个区块号为止。
It might take longer than we want, since it has to load all the blocks. If it's too slow, we could have it only go back to a certain block number.
