‘Dulwich is a pure-Python implementation of the Git file formats and protocols.’

You want this.

‘Similarly a DVCS encourages check-pointing of work: committing incomplete changes, that may not even compile or pass tests, to your local repository.’ Martin Fowler identifies a key point here.

‘This is the website for the Pro Git book, written by Scott Chacon and published by Apress. Here you can find the full content of the book, a blog with tips and updates about Git and the book and open source projects related to Git or referenced in the book.’

Looks promising.

An attempt to explain how Git works without resorting to compsci terminology.

‘Grit gives you object oriented read/write access to Git repositories via Ruby. The main goals are stability and performance.’ Used by GitHub.

How Git solves what he calls ‘The Tangled Working Copy Problem’ (i.e. where your current changeset comprises multiple conceptual changes).