pack-objects: fix thinko in revalidate code

When revalidating an entry from an existing pack entry->size and
entry->type are not necessarily the size of the final object
when the entry is deltified, but for base objects they must
match.

Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-pack-objects.c

@@ -247,12 +247,13 @@ static int revalidate_one(struct object_entry *entry,
 			  void *data, char *type, unsigned long size)
 {
 	int err;
-	if (!data)
-		return -1;
-	if (size != entry->size)
-		return -1;
-	err = check_sha1_signature(entry->sha1, data, size,
-				   type_names[entry->type]);
+	if ((!data) ||
+	    ((entry->type != OBJ_DELTA) &&
+	     ( (size != entry->size) ||
+	       strcmp(type_names[entry->type], type))))
+		err = -1;
+	else
+		err = check_sha1_signature(entry->sha1, data, size, type);
 	free(data);
 	return err;
 }