Getting Source Code
The old repositories can still be found at http://rpm.org/git/. Additionally a local browsable interface for viewing the repositories is available. Note that the Github repository is authoritative and the local is mirrored and updated from there.
For the RPM repository do:
$ git clone https://github.com/rpm-software-management/rpm.git
To clone the Maximum RPM repository simply do:
$ git clone git://rpm.org/max-rpm.git
If you want write access, please create an github account (if you do not already have one) and ask for being added to the project.