[Core] PIVX: remove potential_overwrite: BIP34 has always been enforced

ref: #1775

src/coins.cpp

@@ -171,6 +171,7 @@ void CCoinsViewCache::AddCoin(const COutPoint& outpoint, Coin&& coin, bool possi
         }
         fresh = it->second.coins.IsPruned() && !(it->second.flags & CCoinsCacheEntry::DIRTY);
     }
+
     if (it->second.coins.vout.size() <= outpoint.n) {
         it->second.coins.vout.resize(outpoint.n + 1);
     }
@@ -188,9 +189,7 @@ void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight)
     bool fCoinstake = tx.IsCoinStake();
     const uint256& txid = tx.GetHash();
     for (size_t i = 0; i < tx.vout.size(); ++i) {
-        // Pass fCoinbase as the possible_overwrite flag to AddCoin, in order to correctly
-        // deal with the pre-BIP30 occurrances of duplicate coinbase transactions.
-        cache.AddCoin(COutPoint(txid, i), Coin(tx.vout[i], nHeight, fCoinbase, fCoinstake), fCoinbase);
+        cache.AddCoin(COutPoint(txid, i), Coin(tx.vout[i], nHeight, fCoinbase, fCoinstake), false);
     }
 }
 

src/coins.h

@@ -598,9 +598,7 @@ class CCoinsViewCache : public CCoinsViewBacked
 };
 
 //! Utility function to add all of a transaction's outputs to a cache.
-// It assumes that overwrites are only possible for coinbase transactions,
-// TODO: pass in a boolean to limit these possible overwrites to known
-// (pre-BIP34) cases.
+// PIVX: It assumes that overwrites are never possible due to BIP34 always in effect
 void AddCoins(CCoinsViewCache& cache, const CTransaction& tx, int nHeight);
 
 //! Utility function to find any unspent output with a given txid.