old_contents: #!/usr/bin/python3
  '''
   ====================================================================
   Copyright (c) 2016 Barry A Scott.  All rights reserved.
  
   This software is licensed as described in the file LICENSE.txt,
   which you should have received as part of this distribution.
  
   ====================================================================
  
      wb_scm_main.py
  
  '''
  import sys
  
  import wb_main
  import wb_scm_app
  
  
  if __name__ == '__main__':
      sys.exit( wb_main.main( wb_scm_app.WbScmApp, sys.argv ) )
  
new_contents: #!/usr/bin/python3
  '''
   ====================================================================
   Copyright (c) 2016 Barry A Scott.  All rights reserved.
  
   This software is licensed as described in the file LICENSE.txt,
   which you should have received as part of this distribution.
  
   ====================================================================
  
      wb_scm_main.py
  
  '''
  import sys
  MIN_SUPPORTED_PYTHON_VERSION = (3, 5)
  if sys.version_info < MIN_SUPPORTED_PYTHON_VERSION:
      print( 'Error: Must be run using pthon %d.%d or newer' % MIN_SUPPORTED_PYTHON_VERSION )
      sys.exit( 9 )
  
  import wb_main
  import wb_scm_app
  
  if __name__ == '__main__':
      sys.exit( wb_main.main( wb_scm_app.WbScmApp, sys.argv ) )
  
subject: put in a check for minimum python version and report clearly to the developer the problem