gossip: Stop backfilling the future

This was caused by us not checking against the max_blockheight, but rather the
min_blockheight which can be negative with a newly created node. This is still
safe since we check for duplicates anyway in `wallet_filteredblock_add`.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/gossip_control.c

@@ -67,7 +67,7 @@ static void got_filteredblock(struct bitcoind *bitcoind,
 	struct bitcoin_tx_output txo;
 
 	/* Only fill in blocks that we are not going to scan later. */
-	if (bitcoind->ld->topology->min_blockheight > fb->height)
+	if (bitcoind->ld->topology->max_blockheight > fb->height)
 		wallet_filteredblock_add(bitcoind->ld->wallet, fb);
 
 	u32 outnum = short_channel_id_outnum(scid);

tests/test_gossip.py

@@ -1344,9 +1344,8 @@ def test_gossip_announce_invalid_block(node_factory, bitcoind):
 
     # Make sure it's OK once it's caught up.
     sync_blockheight(bitcoind, [l1])
-    
 
-@pytest.mark.xfail(strict=True)
+
 def test_gossip_announce_unknown_block(node_factory, bitcoind):
     """Don't backfill the future!