Git 生成GPG key 报错 `Key generation failed: Timeout` 的解决方法

We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
gpg: agent_genkey failed: Timeout
Key generation failed: Timeout

由于之前没有生成过，所以 $ rm -rf ~/.gnupg 一行命令搞定，再生成就好了。