是因为缺少Powerline字体导致的
执行下面的命令来安装字体：
wget https://raw.githubusercontent.com/powerline/powerline/develop/font/10-powerline-symbols.conf
wget https://raw.githubusercontent.com/powerline/powerline/develop/font/PowerlineSymbols.otf
sudo mkdir /usr/share/fonts/OTF
sudo cp 10-powerline-symbols.conf /usr/share/fonts/OTF/
sudo mv 10-powerline-symbols.conf /etc/fonts/conf.d/
sudo mv PowerlineSymbols.otf /usr/share/fonts/OTF/
重启终端之后就会恢复正常了