Issue #10332: multiprocessing: fix a race condition when a Pool is closed

before all tasks have completed.

diff --cc Lib/test/test_multiprocessing.py
Simple merge

diff --cc Misc/NEWS
index ebc72b4d2670dcb772c129bdee95c5b5bdac2773,f7a741a32aadffac7db3ed4170b1a83a8032e30e..717ff91fa21ad69990fbdc4519bc3bcf1c62e4e6
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -338,12 -58,11 +338,15 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #10332: multiprocessing: fix a race condition when a Pool is closed
+   before all tasks have completed.
+ 
  - Issue #13255: wrong docstrings in array module.
  
 +- Issue #8540: Remove deprecated Context._clamp attribute in Decimal module.
 +
 +- Issue #13235: Added PendingDeprecationWarning to warn() method and function.
 +
  - Issue #9168: now smtpd is able to bind privileged port.
  
  - Issue #12529: fix cgi.parse_header issue on strings with double-quotes and