Fix for blocks whose parent was seen but whose grandparent is missing.
Fix for blocks whose parent was seen but whose grandparent is missing.

gjhiggins/chaincoin-abe,Rimbit/RimbitExplorer,ultracoindev/ultracoin-abe,Max-Coin/maxcoin-abe,ultracoindev/ultracoin-abe,BuckyGreen/latiumexplorer,muchbeli/bitcoin-abe,jonnynewbs/bitcoin-abe,UdjinM6/darkcoin-abe,ultracoindev/ultracoin-abe,leadcoin-reboot/leadcoin-abe,machado-rev/HTMLCoinExplorer,MatthewLM/PeercoinAbeExplorer,MatthewLM/PeercoinAbeExplorer,cryptapus/bitcoin-abe,muchbeli/bitcoin-abe,gjhiggins/abe-bee2,Cybnate/NuBits-Abe-explorer,machinecoin-project/machinecoin-blockchainexplorer-abe,ultracoindev/ultracoin-abe,BuckyGreen/latiumexplorer,mmitech/bitcoin-abe,Rimbit/RimbitExplorer,gjhiggins/altcoin-abe,muchbeli/bitcoin-abe,machado-rev/HTMLCoinExplorer,jonnynewbs/bitcoin-abe,machado-rev/HTMLCoinExplorer,BuckyGreen/latiumexplorer,n00bsys0p/altcoin-abe,Dilmacoin/dilmacoin-abe,Rimbit/RimbitExplorer,CraigsCoin/abe-craigscoin,machinecoin-project/machinecoin-blockchainexplorer-abe,gjhiggins/abe-bee2,n00bsys0p/altcoin-abe,jeorgen/bitcoin-abe,Serya05/bitcoin-abe,leadcoin-reboot/leadcoin-abe,machado-rev/HTMLCoinExplorer,Cybnate/NuBits-Abe-explorer,Cybnate/NuBits-Abe-explorer,ultracoindev/ultracoin-abe,Max-Coin/maxcoin-abe,UdjinM6/darkcoin-abe,Cybnate/NuBits-Abe-explorer,MatthewLM/PeercoinAbeExplorer,mmitech/bitcoin-abe,jeromewu/bitcoin-abe-opennet,gjhiggins/abe-bee2,jeorgen/bitcoin-abe,gjhiggins/chaincoin-abe,Cybnate/NuBits-Abe-explorer,Serya05/bitcoin-abe,gjhiggins/altcoin-abe,BuckyGreen/latiumexplorer,Dilmacoin/dilmacoin-abe,muchbeli/bitcoin-abe,MatthewLM/PeercoinAbeExplorer,CraigsCoin/abe-craigscoin,cryptapus/bitcoin-abe,jeromewu/bitcoin-abe-opennet,Rimbit/RimbitExplorer