Solution to Homebrew upgrade issue after MacOS Sierra 12.12.x Upgrade

For anyone who has problems in upgrading Homebrew repository after upgrading to MacOS Sierra 12.12.

$
$ cd "$(brew --repo)" && git fetch && git reset --hard origin/master && brew update
$ brew update
$ brew upgrade
$ brew cleanup
$ brew cask install --force $(brew cask list)
$ brew cask cleanup
$

If you have changed permissions on folder /usr/local while installing Homebrew previously on El Capitan 10.11, you might want to run the following command to revert that change whereas new Homebrew doesn't need special permission over this folder:

$
$ sudo chown root:wheel /usr/local
$