[3.14] gh-74389: gh-70560: subprocess.Popen.communicate() now ignores stdin.flush...

[3.14] gh-74389: gh-70560: subprocess.Popen.communicate() now ignores stdin.flush error when closed (GH-142061) (#142064)

gh-74389: gh-70560: subprocess.Popen.communicate() now ignores stdin.flush error when closed (GH-142061)

gh-70560: gh-74389: subprocess.Popen.communicate() now ignores stdin.flush error when closed

with a unittest and news entry.
(cherry picked from commit 923056b2d41c4c28ad9163901053cd3824d775c5)

Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>