Debian 包 at 的 Copyright 里有那么一段话:"This may be considered the experimental upstream source, and since there doesn't seem to be any other upstream source, the only upstream source." 它没有说明上游 在哪里,而是指明上游的源是 experimental. 不知其他发行版用的什么源? 有没有更好的 at 呢?