Avoid unnecessary database access for unknown transactions

src/main.cpp

@@ -4344,10 +4344,12 @@ bool static AlreadyHave(const CInv& inv) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
                 recentRejects->reset();
             }
 
+            // Use pcoinsTip->HaveCoinsInCache as a quick approximation to exclude
+            // requesting or processing some txs which have already been included in a block
             return recentRejects->contains(inv.hash) ||
                    mempool.exists(inv.hash) ||
                    mapOrphanTransactions.count(inv.hash) ||
-                   pcoinsTip->HaveCoins(inv.hash);
+                   pcoinsTip->HaveCoinsInCache(inv.hash);
         }
     case MSG_BLOCK:
         return mapBlockIndex.count(inv.hash);