For a project named (and with the repository and server user name) 'example'.
ssh example@sojourner.mayfirst.org
cd example
git pull
For the git pull to work your public key must be in /home/vlad/.ssh/authorized_keys on the test server (simone.mayfirst.org). You can get this value from /home/yourusername/.ssh/authorized_keys. (@Stefan can we in some way give people with access to simone access to use it as the vlad user automatically?)