In order to setup auto completions in git source the completions from here:
. /usr/share/bash-completion/completions/git
You can easily have this available by adding . /usr/share/bash-completion/completions/git
as a line in your ~/.bashrc
file and source it using:
. ~/.bashrc
From here on you are able to tab to auto complete branch names etc.
I hope someone out there found this helpful :)