old_contents: #!/usr/bin/env python
  
  from setuptools import setup
  
  setup(
      setup_requires=['pbr>=1.9', 'setuptools>=33.0'],
      pbr=True,
  )
  
new_contents: #!/usr/bin/env python
  
  from setuptools import setup
  
  setup(
      setup_requires=['pbr>=3.1', 'setuptools>=36.0'],
      pbr=True,
  )
  
subject: Bump pbr version