Here are the exact commands to get, build, test and hack on the master branch of apt as of 2/27/2016 on Ubuntu 16.04.1 AMD64.
Get
sudo apt-get install git
git clone https://github.com/Debian/apt
Build
sudo apt-get install \
cmake \
libevent-pthreads-2.0-5 \
libdb5.3 \
libdb5.3-dev \
libcurl4-gnutls-dev \
zlib1g-dev \
libbz2-dev \ liblzma-dev \
liblz4-dev \
docbook-xsl \
doxygen \
libgtest-dev
cd apt
cmake .
sudo apt-get install \
po4a \
xsltproc \
w3m
make all
Test
./test/integration/run-tests
Hack
sudo apt-get install vim
vim
In vim do: setlocal shiftwidth=3 noexpandtab tabstop=8
Discussion and patch submission on the mailing list: deity@lists.debian.org (archive)
Tip
To find the packages installed on your system [1]:
cat /var/lib/dpkg/status
Note
Official git: git://anonscm.debian.org/apt/apt.git
Branch: master
Reference
1. https://github.com/Debian/apt
