以下命令有什么问题：
git remote add linux https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
git clone linux --depth 1 --branch linux-4.19.y
fatal: 仓库 'linux' 不存在
下面这条命令却成功了，
git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git --depth 1 --branch linux-4.19.y
正克隆到 'linux'...
remote: Enumerating objects: 65589, done.
remote: Counting objects: 100% (65589/65589), done.
remote: Compressing objects: 100% (63731/63731), done.