Install git from source under Ubuntu 18.04

get-git.sh

sudo apt install git
git clone git@github.com:git/git.git
cd git/
git checkout v2.15.1
sudo apt install libcurl4-openssl-dev
make configure
./configure --prefix=/usr/local # --without-tcltk
make all man
# make NO_GETTEXT=yes all man
make install install-man

sudo apt purge git

# Or you can keep the package version of git and it should be shadowed
# by the version you compiled.

# Prevent the completion file from being overwritten by the package update.
# sudo dpkg-divert --divert /usr/share/bash-completion/completions/git~ \
#      --add /usr/share/bash-completion/completions/git

# Bash completion for git
sudo cp contrib/completion/git-completion.bash \
     /usr/share/bash-completion/completions/git