跟往常一样，一日不升级本机包版本就一日不舒服。今天就踩坑了

➜  ~ brew update
fatal: could not read Username for 'https://github.com': terminal prompts disabled
Error: Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-completions failed!

怎么解决呢？

➜  ~ brew untap homebrew/homebrew-completions
Untapping homebrew/completions...
Untapped (105 files, 71.0KB).

➜  ~ brew update
Already up-to-date.