http://www.dwheeler.com/essays/scm-security.html
Has basics in English, CompSci work, high-assurance considerations, and some example projects. A bright, security researcher that's very familiar with DVCS's should redo this in light of them with similar recommendations. More like a team of bright researchers but it needs to be done. I'm interested in any papers people already have on this that have similarly-thorough treatment of threat model and proposed mitigations.
Once you know builds, you might want to address subversion, design, implementations, covert channels, and other things if you're trying to stop Five Eyes, Russia, or China. That requires "high-assurance" security methods... when it's even possible... Got a small list here to get people started on how deep the issue goes just at high-level and subversion aspects: