USTC 科大原本的源

deb http://mirrors.ustc.edu.cn/raspbian/raspbian/ wheezy main non-free contrib
deb-src http://mirrors.ustc.edu.cn/raspbian/raspbian/ wheezy main non-free contrib

改成

deb http://mirrors.ustc.edu.cn/raspbian/raspbian/ jessie main non-free contrib
deb-src http://mirrors.ustc.edu.cn/raspbian/raspbian/ jessie main non-free contrib