Replace-by-fee RPC test fails on master #7120

$ ./replace-by-fee.py 
Initializing test directory /tmp/testXh5dZU
Running test simple doublespend...
Running test doublespend chain...
JSONRPC error: 64: too-long-mempool-chain

This is because of

main.h:52:static const unsigned int DEFAULT_ANCESTOR_LIMIT = 25;

The code starts with 50 COINs and spends 1 COIN until 10 COINs remain.

This helps here:

diff --git a/qa/rpc-tests/replace-by-fee.py b/qa/rpc-tests/replace-by-fee.py
index 537a1ed..5c8b642 100755
--- a/qa/rpc-tests/replace-by-fee.py
+++ b/qa/rpc-tests/replace-by-fee.py
@@ -145,7 +145,7 @@ class ReplaceByFeeTest(BitcoinTestFramework):
     def test_doublespend_chain(self):
         """Doublespend of a long chain"""

-        initial_nValue = 50*COIN
+        initial_nValue = 30*COIN
         tx0_outpoint = make_utxo(self.nodes[0], initial_nValue)

         prevout = tx0_outpoint
@@ -162,10 +162,10 @@ class ReplaceByFeeTest(BitcoinTestFramework):
             prevout = COutPoint(int(txid, 16), 0)

         # Whether the double-spend is allowed is evaluated by including all
-        # child fees - 40 BTC - so this attempt is rejected.
+        # child fees - 20 BTC - so this attempt is rejected.
         dbl_tx = CTransaction()
         dbl_tx.vin = [CTxIn(tx0_outpoint, nSequence=0)]
-        dbl_tx.vout = [CTxOut(initial_nValue - 30*COIN, CScript([1]))]
+        dbl_tx.vout = [CTxOut(initial_nValue - 20*COIN, CScript([1]))]
         dbl_tx_hex = txToHex(dbl_tx)

         try:

But then it fails in Running test doublespend tree... with

Running test simple doublespend...
Running test doublespend chain...
Running test doublespend tree...
JSONRPC error: 64: too-long-mempool-chain

@sdaftuar @petertodd ping