new_contents: """TemporaryDirectory class, copied from Python 3.2.
  
  This is copied from the stdlib and will be standard in Python 3.2 and onwards.
  """
  
  # This code should only be used in Python versions < 3.2, since after that we
  # can rely on the stdlib itself.
  try:
      from tempfile import TemporaryDirectory
  
  except ImportError:
      
      import os as _os
      from tempfile import mkdtemp, template
  
      class TemporaryDirectory(object):
          """Create and return a temporary directory.  This has the same
          behavior as mkdtemp but can be used as a context manager.  For
          example:
  
              with TemporaryDirectory() as tmpdir:
                  ...
  
          Upon exiting the context, the directory and everthing contained
          in it are removed.
          """
  
          def __init__(self, suffix="", prefix=template, dir=None):
              self.name = mkdtemp(suffix, prefix, dir)
              self._closed = False
  
          def __enter__(self):
              return self.name
  
          def cleanup(self):
              if not self._closed:
                  self._rmtree(self.name)
                  self._closed = True
  
          def __exit__(self, exc, value, tb):
              self.cleanup()
  
          __del__ = cleanup
  
  
          # XXX (ncoghlan): The following code attempts to make
          # this class tolerant of the module nulling out process
          # that happens during CPython interpreter shutdown
          # Alas, it doesn't actually manage it. See issue #10188
          _listdir = staticmethod(_os.listdir)
          _path_join = staticmethod(_os.path.join)
          _isdir = staticmethod(_os.path.isdir)
          _remove = staticmethod(_os.remove)
          _rmdir = staticmethod(_os.rmdir)
          _os_error = _os.error
  
          def _rmtree(self, path):
              # Essentially a stripped down version of shutil.rmtree.  We can't
              # use globals because they may be None'ed out at shutdown.
              for name in self._listdir(path):
                  fullname = self._path_join(path, name)
                  try:
                      isdir = self._isdir(fullname)
                  except self._os_error:
                      isdir = False
                  if isdir:
                      self._rmtree(fullname)
                  else:
                      try:
                          self._remove(fullname)
                      except self._os_error:
                          pass
              try:
                  self._rmdir(path)
              except self._os_error:
                  pass
  
subject: Add context manager for temporary directories from Python 3.2