Auto append --app to heroku bin according to ENV['HEROKU_APP']

heroku.py

#!/usr/bin/env python
#
# A simple wrapper support select app by reading from environment vars and
# auto append the --app to origin heroku bin.
#
# Last-updated: Fri Dec  6 17:19:07 CST 2013 by quanlong.

import sys
import os
import subprocess

# Delegate to heroku binary.
sys.argv[0] = '/usr/bin/heroku'

if len(sys.argv) > 2 and 'HEROKU_APP' in os.environ:
    sys.argv.insert(2, '--app')
    sys.argv.insert(3, os.environ['HEROKU_APP'])

print sys.argv
subprocess.call(sys.argv)