I like to pride myself on never having used a clumsy phrase like that. That said, machine users were en vogue at GitHub, although maybe that's changing with more consideration being given to deploy keys nowadays.
Edit: and to paint a more complete picture, you pointed out in your answer that many folks were using deploy keys to promote from a development branch to the master branch. Some commenters in this thread may, like myself, just not have thought to use deploy keys for this purpose, or that others would want to.