Merge branch 'bc/object-id'

* bc/object-id: (53 commits)
  object: convert parse_object* to take struct object_id
  tree: convert parse_tree_indirect to struct object_id
  sequencer: convert do_recursive_merge to struct object_id
  diff-lib: convert do_diff_cache to struct object_id
  builtin/ls-tree: convert to struct object_id
  merge: convert checkout_fast_forward to struct object_id
  sequencer: convert fast_forward_to to struct object_id
  builtin/ls-files: convert overlay_tree_on_cache to object_id
  builtin/read-tree: convert to struct object_id
  sha1_name: convert internals of peel_onion to object_id
  upload-pack: convert remaining parse_object callers to object_id
  revision: convert remaining parse_object callers to object_id
  revision: rename add_pending_sha1 to add_pending_oid
  http-push: convert process_ls_object and descendants to object_id
  refs/files-backend: convert many internals to struct object_id
  refs: convert struct ref_update to use struct object_id
  ref-filter: convert some static functions to struct object_id
  Convert struct ref_array_item to struct object_id
  Convert the verify_pack callback to struct object_id
  Convert lookup_tag to struct object_id
  ...

refs.c

@@ -883,9 +883,9 @@ struct ref_update *ref_transaction_add_update(
 	update->flags = flags;
 
 	if (flags & REF_HAVE_NEW)
-		hashcpy(update->new_sha1, new_sha1);
+		hashcpy(update->new_oid.hash, new_sha1);
 	if (flags & REF_HAVE_OLD)
-		hashcpy(update->old_sha1, old_sha1);
+		hashcpy(update->old_oid.hash, old_sha1);
 	update->msg = xstrdup_or_null(msg);
 	return update;
 }