Setup and deployment are combined in one step,
the files to be deployed must be prepared in a previous step.
This poses some restrictions on how the repository can be initialized,
in particular for a nonstandard path argument only orphan = TRUE
can be supported (and will be used).
For more control, create two separate steps with
step_setup_push_deploy() and step_do_push_deploy(),
and create the files to be deployed inbetween these steps.