old_contents: import collections
  import os
  import site
  import sys
  from distutils.sysconfig import get_python_lib
  
  SITE_PACKAGES_PATHS = set()
  if hasattr(site, 'getsitepackages'):
      SITE_PACKAGES_PATHS.update(site.getsitepackages())
  if hasattr(site, 'getusersitepackages'):
      SITE_PACKAGES_PATHS.add(site.getusersitepackages())
  SITE_PACKAGES_PATHS.add(get_python_lib())
  SITE_PACKAGES_PATHS = tuple(SITE_PACKAGES_PATHS)
  
  SYS_PREFIX_PATHS = set((
      sys.prefix,
      sys.exec_prefix,
      os.path.dirname(os.__file__),
      os.path.dirname(collections.__file__),
  ))
  for prop in 'real_prefix', 'real_exec_prefix', 'base_prefix', 'base_exec_prefix':
      if hasattr(sys, prop):
          SYS_PREFIX_PATHS.add(getattr(sys, prop))
  SYS_PREFIX_PATHS = tuple(SYS_PREFIX_PATHS)
  
new_contents: import collections
  import os
  import site
  import sys
  from distutils.sysconfig import get_python_lib
  
  SITE_PACKAGES_PATHS = set()
  if hasattr(site, 'getsitepackages'):
      SITE_PACKAGES_PATHS.update(site.getsitepackages())
  if hasattr(site, 'getusersitepackages'):
      SITE_PACKAGES_PATHS.add(site.getusersitepackages())
  SITE_PACKAGES_PATHS.add(get_python_lib())
  SITE_PACKAGES_PATHS = tuple(SITE_PACKAGES_PATHS)
  
  SYS_PREFIX_PATHS = {
      sys.prefix,
      sys.exec_prefix,
      os.path.dirname(os.__file__),
      os.path.dirname(collections.__file__),
  }
  for prop in 'real_prefix', 'real_exec_prefix', 'base_prefix', 'base_exec_prefix':
      if hasattr(sys, prop):
          SYS_PREFIX_PATHS.add(getattr(sys, prop))
  
  SYS_PREFIX_PATHS = tuple(sorted(SYS_PREFIX_PATHS, key=len, reverse=True))
  
subject: Sort by longest path (assuming stdlib stuff will be in the longest).