Comment 6 for bug 1335116

Erik: You need to use git.

apt install git
mkdir Sandbox
cd Sandbox
git clone https://github.com/linuxmint/mintupdate.git
cd mintupdate
./test

or to make a package and install it.. add the Source repositories using mintsources and run:

apt update
apt build-dep mintupdate
apt install git dpkg-dev debhelper
mkdir Sandbox
cd Sandbox
git clone https://github.com/linuxmint/mintupdate.git
cd mintupdate
dpkg-buildpackage
sudo dpkg -i ../*.deb