The forkserver intermediate process is an implementation detail.  However, if you Ctrl-C the main process, the forkserver process will exit with a KeyboardInterrupt traceback, even if the main process catches KeyboardInterrupt to exit silently.  This produces stderr such as:

$ ./python forkserversignal.py 
^CTraceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/antoine/cpython/default/Lib/multiprocessing/forkserver.py", line 164, in main
    rfds = [key.fileobj for (key, events) in selector.select()]
  File "/home/antoine/cpython/default/Lib/selectors.py", line 445, in select
    fd_event_list = self._epoll.poll(timeout, max_ev)
KeyboardInterrupt


For the sake of usability, forkserver should probably silence those tracebacks by default, for example by changing the default signal handler in the forkserver process (but children forked by the forkserver process should probably get the default Python signal handlers...).

Not sure this can be considered a bugfix or an enhancement.