Set object type at object creation time, not object parse time.

Otherwise we can have objects without a type, which is not good.

commit.c

@@ -12,6 +12,7 @@ struct commit *lookup_commit(unsigned char *sha1)
 		struct commit *ret = malloc(sizeof(struct commit));
 		memset(ret, 0, sizeof(struct commit));
 		created_object(sha1, &ret->object);
+		ret->object.type = commit_type;
 		return ret;
 	}
 	if (obj->parsed && obj->type != commit_type) {
@@ -56,7 +57,6 @@ int parse_commit(struct commit *item)
 	if (strcmp(type, commit_type))
 		return error("Object %s not a commit",
 			     sha1_to_hex(item->object.sha1));
-	item->object.type = commit_type;
 	get_sha1_hex(bufptr + 5, parent);
 	item->tree = lookup_tree(parent);
 	add_ref(&item->object, &item->tree->object);

tree.c

@@ -77,6 +77,7 @@ struct tree *lookup_tree(unsigned char *sha1)
 		struct tree *ret = malloc(sizeof(struct tree));
 		memset(ret, 0, sizeof(struct tree));
 		created_object(sha1, &ret->object);
+		ret->object.type = tree_type;
 		return ret;
 	}
 	if (obj->parsed && obj->type != tree_type) {
@@ -96,7 +97,6 @@ int parse_tree(struct tree *item)
 	if (item->object.parsed)
 		return 0;
 	item->object.parsed = 1;
-	item->object.type = tree_type;
 	buffer = bufptr = read_sha1_file(item->object.sha1, type, &size);
 	if (!buffer)
 		return error("Could not read %s",