Bugfix for database checksum reconstruction with zero blocks.

diff --git a/python/cumulus/rebuild_database.py b/python/cumulus/rebuild_database.py
index 39bf7c1..10a5f9a 100755 (executable)
--- a/python/cumulus/rebuild_database.py
+++ b/python/cumulus/rebuild_database.py
@@ -301,6 +301,9 @@ class DatabaseRebuilder(object):
             buf = fp.read(length)
             verifier.update(buf)
 
+            # Zero blocks get no checksums, so skip further processing on them.
+            if object is None: continue
+
             if exact:
                 csum = cumulus.ChecksumCreator(CHECKSUM_ALGORITHM)
                 csum.update(buf)