Extract of patch by Ronald Oussoren.

See https://github.com/python/asyncio/pull/292 for details.

See https://github.com/python/asyncio/pull/289 for details.

See https://github.com/python/asyncio/pull/291 for details.

Patch by Mark Roseman.

This was triggering intermittent failures in unrelated tests.

internals regarding how fds_to_pass were passed to the child.  The bug
had no actual impact as subprocess.py already avoided it.

not allow the send_signal(), terminate(), or kill() methods to do
anything as they could potentially signal a different process.

not allow the send_signal(), terminate(), or kill() methods to do
anything as they could potentially signal a different process.

with a null byte.

with a null byte.

Mainly missing grammatical articles (the, a).