From 90a9019387450e4e22285daff3b4f2ccdb42c598 Mon Sep 17 00:00:00 2001
From: Simon <simon@bitcartel.com>
Date: Wed, 27 Jul 2016 00:52:27 -0700
Subject: [PATCH] Fix issue where a coinbase tx should have it's sigscript
 hashed to avoid duplicate txids, as discussed in BIP34 and BIP30.

---
 src/primitives/transaction.cpp | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/primitives/transaction.cpp b/src/primitives/transaction.cpp
index 114aaf372..5d157a5c3 100644
--- a/src/primitives/transaction.cpp
+++ b/src/primitives/transaction.cpp
@@ -234,13 +234,16 @@ void CTransaction::UpdateTxid() const
     // Create a deep copy of this transaction
     CMutableTransaction tx(*this);
 
-    // Clear sigscript from all transaction inputs.
-    for (CTxIn & txIn : tx.vin) {
-        txIn.scriptSig.clear();
-    }
+    // We keep the sigscript for coinbase txs to avoid duplicate txids (BIP34 and BIP30)
+    if (!IsCoinBase()) {
+        // Clear sigscript from all transaction inputs.
+        for (CTxIn & txIn : tx.vin) {
+            txIn.scriptSig.clear();
+        }
 
-    // Clear joinSplitSig by filling the buffer with zero
-    tx.joinSplitSig.assign(0);
+        // Clear joinSplitSig by filling the buffer with zero
+        tx.joinSplitSig.assign(0);
+    }
 
     // Return double SHA256 hash
     *const_cast<uint256*>(&txid) = tx.GetSerializeHash();