From 4dcefa7d3b937c5e36148ee30566a096a4526b0d Mon Sep 17 00:00:00 2001
From: SomberNight <somber.night@protonmail.com>
Date: Tue, 26 Jun 2018 16:56:30 +0200
Subject: [PATCH] network: fix fork detection in certain backward search cases

if there are no checkpoints and the split is very old, the exponential backward search might undershoot so that it asks for the genesis block but 0 and None are not distinguished hence the fork detection logic fails
---
 lib/network.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/network.py b/lib/network.py
index 75619b924..3d9d031fa 100644
--- a/lib/network.py
+++ b/lib/network.py
@@ -974,7 +974,7 @@ class Network(util.DaemonThread):
         else:
             raise Exception(interface.mode)
         # If not finished, get the next header
-        if next_height:
+        if next_height is not None:
             if interface.mode == 'catch_up' and interface.tip > next_height + 50:
                 self.request_chunk(interface, next_height // 2016)
             else: