Upstream https://github.com/python/asyncio/pull/408 by Ron Frederick.

Upstream https://github.com/python/asyncio/pull/374 by Ron Frederick.

Patch by Ville Skyttä.

Perhaps the BytesParser 'text' argument should really be bytes, but
it hasn't been, it has been text, so for backward compatibility
and for consistency with the regular Parser class, I'm keeping it
as 'text'.

test_tools is pretty much useless unless somebody copies the scripts
it tests into the proper location, but we might as well install it
anyway to make sure it skips properly.  test_warnings just didn't get
included when it was turned into a package in 94966dfd3bd3.

Issue #27870: A left shift of zero by a large integer no longer attempts to allocate large amounts of memory.