hi,

few comments on this: [when tested with 'spawn']

1. the document(3x, 17.2.1.2) clearly mentions that 'spawn' doesnt inherit the file-handles (hence FileNotFoundError).
2. the document's examples has spawn() followed by join() where parent waits for the Child to finish and exits gracefully. The error "OSError: [Errno 9] Bad file descriptor" is seen for Child process.
3. Isnt exception-handling for null file descriptors sufficient (with corresponding Document updates)

am not a core developer yet and still trying to learn and contribute.

Thanks