rpc: don't go below feerate_floor when converting vbytes

We passed below the floor when the user specified `1000perkb`.
Matt Whitlock says :

    I was withdrawing with feerate=1000perkb, which should be the minimum-allowed fee rate. Indeed, bitcoin-cli getmempoolinfo reports:

    {
      "loaded": true,
      "size": 15097,
      "bytes": 9207924,
      "usage": 32831760,
      "maxmempool": 64000000,
      "mempoolminfee": 0.00001000,
      "minrelaytxfee": 0.00001000
    }

Changelog-fixed: rpc: The `feerate` parameters now correctly handle the standardness minimum when passed as `perkb`.
Signed-off-by: Antoine Poinsot <darosior@protonmail.com>
Reported-by: Matt Whitlock

lightningd/json.c

@@ -1,6 +1,7 @@
 #include <arpa/inet.h>
 #include <bitcoin/address.h>
 #include <bitcoin/base58.h>
+#include <bitcoin/feerate.h>
 #include <bitcoin/script.h>
 #include <ccan/json_escape/json_escape.h>
 #include <ccan/mem/mem.h>
@@ -159,6 +160,8 @@ struct command_result *param_feerate(struct command *cmd, const char *name,
 
 	*feerate = tal(cmd, u32);
 	**feerate = feerate_from_style(num, style);
+	if (**feerate < FEERATE_FLOOR)
+		**feerate = FEERATE_FLOOR;
 	return NULL;
 }
 

tests/test_wallet.py

@@ -15,7 +15,6 @@ import time
 import unittest
 
 
-@pytest.mark.xfail(strict=True)
 @unittest.skipIf(TEST_NETWORK != 'regtest', "Test relies on a number of example addresses valid only in regtest")
 def test_withdraw(node_factory, bitcoind):
     amount = 1000000