static bool is_index_extended(git_index *index)
{
	size_t i, extended;
	git_index_entry *entry;

	extended = 0;

	git_vector_foreach(&index->entries, i, entry) {
		entry->flags &= ~GIT_IDXENTRY_EXTENDED;
		if (entry->flags_extended & GIT_IDXENTRY_EXTENDED_FLAGS) {
			extended++;
			entry->flags |= GIT_IDXENTRY_EXTENDED;
		}
	}

	return (extended > 0);
}

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.