Yeah, the goal of running it through `subprocess` is to run the command in the environment of an entire different project.  What you've set up is just the same as the others--it runs the command in the current Django environment.  I don't believe this will work to run a command in another installation's environment.

This capability was used in the update command (to call into one server from the other) and is used in testing (ecosystem tests).  Not sure beyond this.

Will look farther to see how you worked around this in the code.