The order pytest-django uses for determining which settings file should be used for running tests might not be the most optimal when using environment variables. However, it is still possible to override it so that it picks up the correct file without recurring to extra typing.
Vagrant is an amazing tool. However, one thing that bugged me was that provisioning scripts preparation still required me a fair amount of time and trial-errors attempts. Switching to Ansible allowed me to make my life easier and provision times shorter.