[conformal/btcdb] ca502a: Two fixes

[David Hill]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcdb
  Commit: ca502abbf25575873c751b1434060c052b049b99
      
https://github.com/conformal/btcdb/commit/ca502abbf25575873c751b1434060c052b049b99
  Author: David Hill <dh...@conformal.com>
  Date:   2013-11-26 (Tue, 26 Nov 2013)

  Changed paths:
    M ldb/leveldb.go

  Log Message:
  -----------
  Two fixes

fix returning error on insertTx and doSpend.
clear the batch on failures as well.