brew|brew update 报错＂fatal: Could not resolve HEAD to a revision＂ brewupdate报错

报错
执行brew update命令时：

% brew update error: Not a valid ref: refs/remotes/origin/master fatal: Could not resolve HEAD to a revision Already up-to-date.

解决
% brew update --verbose

% brew update -verbose Checking if we need to fetch /opt/homebrew... Checking if we need to fetch /opt/homebrew/Library/Taps/homebrew/homebrew-cask... Fetching /opt/homebrew... Checking if we need to fetch /opt/homebrew/Library/Taps/homebrew/homebrew-core... Fetching /opt/homebrew/Library/Taps/homebrew/homebrew-core... Fetching /opt/homebrew/Library/Taps/homebrew/homebrew-cask... fatal: unable to access 'https://github.com/Homebrew/homebrew-cask/': Failed to connect to github.com port 443: Operation timed out Error: Fetching /opt/homebrew/Library/Taps/homebrew/homebrew-cask failed! Updating /opt/homebrew... Branch 'master' set up to track remote branch 'master' from 'origin'. Switched to and reset branch 'master' Your branch is up to date with 'origin/master'. Switched to and reset branch 'stable' Current branch stable is up to date.Updating /opt/homebrew/Library/Taps/homebrew/homebrew-core... fatal: Could not resolve HEAD to a revision

打开报错路径：
% cd /opt/homebrew/Library/Taps/homebrew/homebrew-core
% ls -al

total 0 drwxr-xr-x3 tyrone.lin@ui.comadmin964 13 16:34 . drwxr-xr-x4 tyrone.lin@ui.comadmin1284 14 11:31 .. drwxr-xr-x12 tyrone.lin@ui.comadmin3844 14 11:44 .git

执行:
% git fetch --prune origin
% git pull --rebase origin master