diff --git a/swh/indexer/metadata.py b/swh/indexer/metadata.py
--- a/swh/indexer/metadata.py
+++ b/swh/indexer/metadata.py
@@ -277,8 +277,9 @@
         for origin in origins:
             head_result = self.origin_head_indexer.index(origin)
             if not head_result:
-                continue
-            head_rev_ids.append(head_result['revision_id'])
+                head_rev_ids.append(None)
+            else:
+                head_rev_ids.append(head_result['revision_id'])
 
         head_revs = list(self.storage.revision_get(head_rev_ids))
         assert len(head_revs) == len(head_rev_ids)
@@ -286,8 +287,8 @@
         results = []
         for (origin, rev) in zip(origins, head_revs):
             if not rev:
-                self.warning('Missing head revision %s of origin %r',
-                             (hashutil.hash_to_bytes(rev['id']), origin))
+                self.log.warning('Missing head revision of origin %r',
+                                 origin)
                 continue
 
             rev_metadata = self.revision_metadata_indexer.index(rev)