解决:
// 执行下面这句命令,更换为中科院的镜像:
git clone git://mirrors.ustc.edu.cn/homebrew-core.git/ /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core --depth=1
// 把homebrew-core的镜像地址也设为中科院的国内镜像
cd "$(brew --repo)"
git remote set-url origin https://mirrors.ustc.edu.cn/brew.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://mirrors.ustc.edu.cn/homebrew-core.git
// 更新
brew update