Test prioritisetransaction and ancestor fee state

There is already a similar test for descendant fee state.

test/functional/mempool_packages.py

@@ -101,6 +101,18 @@ class MempoolPackagesTest(BitcoinTestFramework):
             assert_equal(mempool[x], v_descendants[x])
         assert(chain[0] not in v_descendants.keys())
 
+        # Check that ancestor modified fees includes fee deltas from
+        # prioritisetransaction
+        self.nodes[0].prioritisetransaction(chain[0], 1000)
+        mempool = self.nodes[0].getrawmempool(True)
+        ancestor_fees = 0
+        for x in chain:
+            ancestor_fees += mempool[x]['fee']
+            assert_equal(mempool[x]['ancestorfees'], ancestor_fees * COIN + 1000)
+        
+        # Undo the prioritisetransaction for later tests
+        self.nodes[0].prioritisetransaction(chain[0], -1000)
+
         # Check that descendant modified fees includes fee deltas from
         # prioritisetransaction
         self.nodes[0].prioritisetransaction(chain[-1], 1000)