问题：[!] CocoaPods LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to github.com:443

这个问题在github上已有记录
Mac OS 10.14 Mojave brew upgrade Curl LibreSSL SSL_connect: SSL_ERROR_SYSCALL #4436
解决
问题通过设置此env变量解决：
export HOMEBREW_FORCE_BREWED_CURL =1
如果设置上面的还不行，顺便执行下面的两句

git config --global --unset http.proxy
git config --global --unset https.proxy

2、github

Homebrew/brew

Homebrew/brew的github地址：https://github.com/Homebrew