Seeking means to get Fabric to automatically (instead of user-interactively) interact with shell commands (and not just requests for passwords, but also requested user input
It's not either/or. You just need to run the fab command through pexpect:
child = pexpect.spawn('fab ') child.expect('prompt:') child.send('reponse to prompt') ... etc
The fab command is just like any other command, so it can be scripted through pexpect.