old_contents: 
  try:
      from rpclib.util.oset.new import oset
  except (SyntaxError, ImportError, AttributeError), e:
      from rpclib.util.oset.old import oset
  
new_contents: 
  try:
      from rpclib.util.oset.new import oset
  except (SyntaxError, ImportError, AttributeError):
      from rpclib.util.oset.old import oset
  
subject: remove needless exception reference.