bugfix: don't attempt to remove spends from coinbase txs.
bugfix: don't attempt to remove spends from coinbase txs.

kaostao/libbitcoin,libtetcoin/libtetcoin-consensus,libmetrocoin/libmetrocoin-consensus,kaostao/libbitcoin,BWallet/libbitcoin,libmetrocoin/libmetrocoin-consensus,BWallet/libbitcoin,BWallet/libbitcoin,libtetcoin/libtetcoin-consensus,Airbitz/libbitcoin,kaostao/libbitcoin,swansontec/libbitcoin,swansontec/libbitcoin,Airbitz/libbitcoin,Airbitz/libbitcoin,kaostao/libbitcoin,libtetcoin/libtetcoin-consensus,BWallet/libbitcoin,libmetrocoin/libmetrocoin-consensus,libmetrocoin/libmetrocoin-consensus,GroestlCoin/libgroestlcoin,libmetrocoin/libmetrocoin-consensus,swansontec/libbitcoin,Airbitz/libbitcoin,swansontec/libbitcoin,GroestlCoin/libgroestlcoin,libtetcoin/libtetcoin-consensus,GroestlCoin/libgroestlcoin,GroestlCoin/libgroestlcoin,libtetcoin/libtetcoin-consensus