It was hard but I went throught https://secure.phabricator.com/book/phabricator/article/diffusion_hosting/
Alll worked but at the end i get :
sudo: a password is required fatal: Could not read from remote repository. Please make sure you have the correct access rights and the repository exists.
so I get visudo
git ALL=(phabricator) SETENV: NOPASSWD: ALL
And then it works. So it seems that the configs, the hooks and co are working perfectly.
Are you aware of a way to trace file used by sudo ?
Should I dissect the ssh hooks ?