"if not" also triggers when value is 0, use "if is None" instead

diff --git a/grml2usb b/grml2usb
index e2cffe8..e1d7f5c 100755 (executable)
--- a/grml2usb
+++ b/grml2usb
@@ -1556,7 +1556,7 @@ def handle_mbr(device):
         return 0
 
     mbr_device, partition_number = get_device_from_partition(device)
-    if not partition_number:
+    if partition_number is None:
         logging.warn("Could not detect partition number, not activating partition")
 
     # if we get e.g. /dev/loop1 as device we don't want to put the MBR