old_contents: """Activate coverage at python startup if appropriate.
  
  The python site initialisation will ensure that anything we import
  will be removed and not visible at the end of python startup.  However
  we minimise all work by putting these init actions in this separate
  module and only importing what is needed when needed.
  
  For normal python startup when coverage should not be activated the pth
  file checks a single env var and does not import or call the init fn
  here.
  
  For python startup when an ancestor process has set the env indicating
  that code coverage is being collected we activate coverage based on
  info passed via env vars.
  """
  import os
  
  
  def multiprocessing_start(obj):
      cov = init()
      if cov:
          multiprocessing.util.Finalize(None, multiprocessing_finish, args=(cov,), exitpriority=1000)
  
  
  def multiprocessing_finish(cov):
      cov.stop()
      cov.save()
  
  
  try:
      import multiprocessing.util
  except ImportError:
      pass
  else:
      multiprocessing.util.register_after_fork(multiprocessing_start, multiprocessing_start)
  
  
  def init():
      # Only continue if ancestor process has set everything needed in
      # the env.
  
      cov_source = os.environ.get('COV_CORE_SOURCE')
      cov_config = os.environ.get('COV_CORE_CONFIG')
      cov_datafile = os.environ.get('COV_CORE_DATAFILE')
      if cov_datafile:
          # Import what we need to activate coverage.
          import coverage
  
          # Determine all source roots.
          if not cov_source:
              cov_source = None
          else:
              cov_source = cov_source.split(os.pathsep)
          if not cov_config:
              cov_config = True
  
          # Activate coverage for this process.
          cov = coverage.coverage(
              source=cov_source,
              data_suffix=True,
              config_file=cov_config,
              auto_data=True,
              data_file=cov_datafile
          )
          cov.load()
          cov.start()
          cov._warn_no_data = False
          cov._warn_unimported_source = False
          return cov
  
new_contents: """Activate coverage at python startup if appropriate.
  
  The python site initialisation will ensure that anything we import
  will be removed and not visible at the end of python startup.  However
  we minimise all work by putting these init actions in this separate
  module and only importing what is needed when needed.
  
  For normal python startup when coverage should not be activated the pth
  file checks a single env var and does not import or call the init fn
  here.
  
  For python startup when an ancestor process has set the env indicating
  that code coverage is being collected we activate coverage based on
  info passed via env vars.
  """
  import os
  
  
  def multiprocessing_start(_):
      cov = init()
      if cov:
          multiprocessing.util.Finalize(None, multiprocessing_finish, args=(cov,), exitpriority=1000)
  
  
  def multiprocessing_finish(cov):
      cov.stop()
      cov.save()
  
  
  try:
      import multiprocessing.util
  except ImportError:
      pass
  else:
      multiprocessing.util.register_after_fork(None, multiprocessing_start)
  
  
  def init():
      # Only continue if ancestor process has set everything needed in
      # the env.
  
      cov_source = os.environ.get('COV_CORE_SOURCE')
      cov_config = os.environ.get('COV_CORE_CONFIG')
      cov_datafile = os.environ.get('COV_CORE_DATAFILE')
      if cov_datafile:
          # Import what we need to activate coverage.
          import coverage
  
          # Determine all source roots.
          if not cov_source:
              cov_source = None
          else:
              cov_source = cov_source.split(os.pathsep)
          if not cov_config:
              cov_config = True
  
          # Activate coverage for this process.
          cov = coverage.coverage(
              source=cov_source,
              data_suffix=True,
              config_file=cov_config,
              auto_data=True,
              data_file=cov_datafile
          )
          cov.load()
          cov.start()
          cov._warn_no_data = False
          cov._warn_unimported_source = False
          return cov
  
subject: Use none as the object, less confusing.