old_contents: version_info = (0, 9, 0)
  __version__ = '.'.join(map(str, version_info[:3])) + ''.join(version_info[3:])
  
new_contents: version_info = (0, 9, 1, 'dev0')
  __version__ = '.'.join(map(str, version_info[:3])) + ''.join(version_info[3:])
  
subject: bump to 0.9.1.dev0