How do I disown/detach a process from the Git Bash terminal that come with Git's Windows installer?

How do I disown/detach a process from the Git Bash terminal that come with Git's Windows installer?

I would like to run commands from the terminal (mostly Python servers) and essentially daemonize them. I am running the MinGW terminal "Git Bash" that comes with the Windows installer for Git.
Things tried that do not work:
nohup -> command not found
setsid -> command not found
$ script.py & -> does not behave as expected
$ script.py & disown -> does not behave as expected
I would use bg, but my end-goal is to close the terminal after my servers are all running and not kill the processes.