Libgit2 is "a portable, pure C implementation of the Git core methods" started in 2008 by Shawn O. Pearce. It is successfully used in both commercial an open source projects and wrapped in many languages (among the others Ruby, C#, Python). In 2011 Laszlo Papp from KDE started the libqgit2 project, aiming to port libgit2 features to C++/Qt. Sadly, lately the development slowed down a little and the library could not compile against the latest libgit2.
Being interested in using libgit2 in Qt/KDE projects, I am trying to restart the development. I managed to update the library to libgit2 0.19.0 (latest version), and you can find the code on GitHub. Feel free to fork it and work on it, but remember that this is just an unofficial repository.