test: Pass at most one node group to sync_all

test/functional/wallet_listsinceblock.py

@@ -98,7 +98,8 @@ class ListSinceBlockTest (BitcoinTestFramework):
         self.nodes[2].generate(7)
         self.log.info('lastblockhash=%s' % (lastblockhash))
 
-        self.sync_all([self.nodes[:2], self.nodes[2:]])
+        self.sync_all(self.nodes[:2])
+        self.sync_all(self.nodes[2:])
 
         self.join_network()