old_contents: from __future__ import absolute_import, unicode_literals
  from .premailer import Premailer, transform
  
  __version__ = '2.9.0'
  
new_contents: from __future__ import absolute_import, unicode_literals
  from .premailer import Premailer, transform
  
  __version__ = '2.9.1'
  
subject: bump to 2.9.1