Due a mistake introduced while bumping to Git 2.12 (
request #12279), installations done since Tuleap 10.5.99.15 uses Git 1.7 instead of Git 2.12 for gitolite interactions. Instructions given in the deployment guide were correct so the issue only impact fresh installations.
Tuleap manipulation of Git repositories are still done with Git 2.12 even on fresh installs.