message: Transaction builder does not fetch network
  Reviewers: arik
  Subscribers: ben
diff: @@ -742,7 +742,7 @@ exports.signTransaction = function(params) {
  throw new Error('single key address used in input but feeSingleKeyWIF not provided');
  }
  - txb = bitcoin.TransactionBuilder.fromTransaction(transaction, bitcoin.getNetwork());
  + txb = bitcoin.TransactionBuilder.fromTransaction(transaction);
  txb.sign(index, feeSingleKey);
  transaction = txb.buildIncomplete();
  continue;
  @@ -762,7 +762,7 @@ exports.signTransaction = function(params) {
  // In order to sign with bitcoinjs-lib, we must use its transaction
  // builder, confusingly named the same exact thing as our transaction
  // builder, but with inequivalent behavior.
  - txb = bitcoin.TransactionBuilder.fromTransaction(transaction, bitcoin.getNetwork());
  + txb = bitcoin.TransactionBuilder.fromTransaction(transaction);
  try {
  txb.sign(index, privKey, subscript, bitcoin.Transaction.SIGHASH_ALL);
  } catch (e) {
  