old_contents: from spack import *
  
  class PyDateutil(Package):
      """Extensions to the standard Python datetime module."""
      homepage = "https://pypi.python.org/pypi/dateutil"
      url      = "https://pypi.python.org/packages/source/p/python-dateutil/python-dateutil-2.4.0.tar.gz"
  
      version('2.4.0', '75714163bb96bedd07685cdb2071b8bc')
      version('2.4.2', '4ef68e1c485b09e9f034e10473e5add2')
  
      extends('python')
      depends_on('py-setuptools')
      depends_on('py-six')
  
      def install(self, spec, prefix):
          python('setup.py', 'install', '--prefix=%s' % prefix)
  
new_contents: from spack import *
  
  class PyDateutil(Package):
      """Extensions to the standard Python datetime module."""
      homepage = "https://pypi.python.org/pypi/dateutil"
      url      = "https://pypi.python.org/packages/source/p/python-dateutil/python-dateutil-2.4.0.tar.gz"
  
      version('2.4.0', '75714163bb96bedd07685cdb2071b8bc')
      version('2.4.2', '4ef68e1c485b09e9f034e10473e5add2')
      version('2.5.2', 'eafe168e8f404bf384514f5116eedbb6')
  
      extends('python')
      depends_on('py-setuptools')
      depends_on('py-six')
  
      def install(self, spec, prefix):
          python('setup.py', 'install', '--prefix=%s' % prefix)
  
subject: Add version 2.5.2.