[conformal/btcwallet] 29fef9: Fix nil pointer dereference.

[Josh Rickmar]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcwallet
  Commit: 29fef9ffd27143c4518610be74748e98cfcd4237
      
https://github.com/conformal/btcwallet/commit/29fef9ffd27143c4518610be74748e98cfcd4237
  Author: Josh Rickmar <jr...@conformal.com>
  Date:   2014-03-18 (Tue, 18 Mar 2014)

  Changed paths:
    M tx/tx.go

  Log Message:
  -----------
  Fix nil pointer dereference.

Ran into by @toddfries and brought up on IRC.