Have you ever needed or wanted to pull a remote Git Repository on Drupal.org down as a zip or tarball? You know, the way Github does? Most project releases have fairly recently built tarballs which is awesome - but Sandboxes do not (so it seems - please correct me if I'm wrong!).
The following snippet lets you "archive" a remote repository, pull it down as a tarball, and extract it in-place:
git archive --format=tar --prefix=PROJECT/ --remote=USERNAME@git.drupal.org:sandbox/USERNAME/123456789.git BRANCH | tar -xf -