brew installしたときにpkg-configでsyntax errorが起きる場合の対処法

> brew install any-package-name
Error: pkg-config: /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/pkg-config.rb:1: syntax error, unexpected <<
<<<<<<< HEAD
  ^
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/pkg-config.rb:41: syntax error, unexpected ===, expecting end-of-input
=======
   ^

こんなときは

brew update-reset

で一発解決