pa_create_webapp_with_virtualenv.py is expecting a <git-repo-url> like the Django script, but it's not docopt specified, so a KeyError ensues:
Traceback (most recent call last):
File "scripts/pa_create_webapp_with_virtualenv.py", line 51, in <module>
main(arguments['<git-repo-url>'], arguments['--domain'], arguments['--python'], nuke=arguments.get('--nuke'))
KeyError: '<git-repo-url>'
Even if <git-repo-url> is added to the docopt spec, the variable isn't currently used for checkout like it is in the Django version.