wic: improve generating disk system identifier

This should reduce the chance of generating 0xffffffff as the disk
system identifier.

(From OE-Core rev: 5619e72facbc9228d3cf8f844f198e03b536ac8c)

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/plugins/imager/direct.py

@@ -26,6 +26,7 @@
 
 import logging
 import os
+import random
 import shutil
 import tempfile
 import uuid
@@ -303,7 +304,7 @@ class PartitionedImage():
                           # all partitions (in bytes)
         self.ptable_format = ptable_format  # Partition table format
         # Disk system identifier
-        self.identifier = int.from_bytes(os.urandom(4), 'little') or 0xffffffff
+        self.identifier = random.SystemRandom().randint(1, 0xffffffff)
 
         self.partitions = partitions
         self.partimages = []