Handle generate_signature_hash() error sentinel.
Handle generate_signature_hash() error sentinel.

cancoin/libbitcoin-explorer,GroestlCoin/libgroestlcoin-explorer,GroestlCoin/libgroestlcoin-explorer,GroestlCoin/libgroestlcoin-explorer,libtetcoin/libtetcoin-explorer,cancoin/libbitcoin-explorer,libmetrocoin/libmetrocoin-explorer,tuomassiren/libbitcoin-explorer,libmetrocoin/libmetrocoin-explorer,libtetcoin/libtetcoin-explorer,tuomassiren/libbitcoin-explorer