fix(BlockStream): fix getting transactions for Merkle blocks

Would previously always emit empty transaction arrays, even if there should be a matched transaction.

lib/blockStream.js

@@ -135,13 +135,19 @@ BlockStream.prototype._getTransactions = function (txids, cb) {
       hash: u.toHash(txid)
     })
   })
-  var message = this.peers.messages.GetData(inventory)
-  var transactions = []
+  var peer = this._getPeer()
+  var message = peer.messages.GetData(inventory)
+  var remaining = txids.length
+  var transactions = new Array(txids.length)
   function onTx (res) {
-    var index = txids.indexOf(res.transaction.id)
-    if (index === -1) return
-    txids.splice(index, 1)
-    if (txids.length === 0) {
+    var txid = u.toHash(res.transaction.id)
+    for (var i = 0; i < txids.length; i++) {
+      if (txids[i].compare(txid) === 0) break
+    }
+    if (i === txids.length) return
+    transactions[i] = res.transaction
+    remaining--
+    if (remaining === 0) {
       self.removeListener('tx', onTx)
       cb(null, transactions)
     }