Where to find the Debian git repos?
The important Debian development repos are hosted on the Alioth server.
You can access them using http(s), git or SSH protocol using the address:
For example, to clone the anna project, which is part of the debian-installer programmes you will run:
$> git clone http://anonscm.debian.org/git/d-i/anna
Note that git is not the only VCS used on Alioth.