Install git from source

upgrade_git.sh

#!/bin/bash

if which apt-get 2>&1 >/dev/null; then
  sudo apt-get install -y libcurl4-gnutls-dev libexpat1-dev gettext libz-dev libssl-dev
fi

cd ~/src

[[ ! -d git ]] && git clone https://github.com/git/git --depth 10

cd git
git fetch origin v2.5.0 --depth 1
git checkout FETCH_HEAD
make prefix=/usr/local all
sudo make prefix=/usr/local install

This script clone git to ~/src, checkout v2.5.0 and install to /usr/local.