old_contents: #!/usr/bin/env python
  
  """Call the main setup_git.py. This should be
  copied to the main directory of your project and named setup_git.py."""
  
  import os
  import os.path
  os.system(os.path.join("tools", "dev_tools", "git", "setup_git.py"))
  
new_contents: #!/usr/bin/env python3
  
  """Call the main setup_git.py. This should be
  copied to the main directory of your project and named setup_git.py."""
  
  import os
  import os.path
  os.system(os.path.join("tools", "dev_tools", "git", "setup_git.py"))
  
subject: Use Python 3 by default