old_contents: from   __future__ import unicode_literals
  import platform
  
  __version__ = '0.3.0'
  
  USER_AGENT = 'daemail {} ({} {})'.format(
      __version__, platform.python_implementation(), platform.python_version()
  )
  
new_contents: from   __future__ import unicode_literals
  import platform
  
  __version__ = '0.3.0.dev1'
  
  USER_AGENT = 'daemail {} ({} {})'.format(
      __version__, platform.python_implementation(), platform.python_version()
  )
  
subject: Mark current code as a dev version