The following will help get GIT completion setup locally on Mac Sierra. Not correctly loading the git-completion.bash or git-prompt.sh can result in getting the following error:
ERROR: __git_ps1: command not found
Check that you did not mistype the file name as that could result in the script not being found and ran.
STEPS:
$ cd ~/Downloads
$ curl -OL https://github.com/git/git/raw/master/contrib/completion/git-completion.bash
$ mv git-completion.bash ~/.git-completion.bash
$ sudo nano ~/.bashrc
ADD .bashrc CONTENTS
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if [ -f ~/.git-completion.bash ]; then
source ~/.git-completion.bash
fi
$ cd ~/Downloads/
$ curl -OL https://raw.githubusercontent.com/git/git/master/contrib/completion/git-prompt.sh
$ mv ~/Downloads/git-prompt.sh ~/.git-prompt.sh
UPDATE .bash_profile CONTENTS
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if [ -f ~/.git-prompt.sh ]; then
source ~/.git-prompt.sh
fi
export PS1='\h:\u \W$(__git_ps1 "(%s)") $ '