已确认，他们的系统目前仍存在问题：
fatal: remote error: GitHub is temporarily limiting some unauthenticated downloads to protect the stability of the platform. Please retry later or authenticate.
could not read Username for '``https://github.com/``': No such device or address
这次 GitHub 状态页面（https://www.githubstatus.com/）并未发布相关公告，但影响与八月份的事件相当。
也许是时候迁移到 GitLab 了。