Auto merge of #1019 - ebfull:mempool-integrity-chained-pours, r=ebfull

Ensure mempool integrity checks don't trip on chained joinsplits.

src/txmempool.cpp

@@ -314,14 +314,28 @@ void CTxMemPool::check(const CCoinsViewCache *pcoins) const
             assert(it3->second.n == i);
             i++;
         }
+
+        boost::unordered_map<uint256, ZCIncrementalMerkleTree, CCoinsKeyHasher> intermediates;
+
         BOOST_FOREACH(const CPourTx &pour, tx.vpour) {
             BOOST_FOREACH(const uint256 &serial, pour.serials) {
                 assert(!pcoins->GetSerial(serial));
             }
 
-            // TODO: chained pours
             ZCIncrementalMerkleTree tree;
-            assert(pcoins->GetAnchorAt(pour.anchor, tree));
+            auto it = intermediates.find(pour.anchor);
+            if (it != intermediates.end()) {
+                tree = it->second;
+            } else {
+                assert(pcoins->GetAnchorAt(pour.anchor, tree));
+            }
+
+            BOOST_FOREACH(const uint256& commitment, pour.commitments)
+            {
+                tree.append(commitment);
+            }
+
+            intermediates.insert(std::make_pair(tree.root(), tree));
         }
         if (fDependsWait)
             waitingOnDependants.push_back(&it->second);