Use proper gettext plural forms in optparse (closes #4391).

Original patch by Dwayne Bailey.
diff --git a/Misc/NEWS b/Misc/NEWS
index 7557baf..3101327 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -75,6 +75,8 @@
 Library
 -------
 
+- Issue #4391: Use proper gettext plural forms in optparse.
+
 - Issue #11563: Connection:close header is sent by requests using URLOpener
   class which helps in closing of sockets after connection is over. Patch
   contributions by Jeff McNeil and Nadeem Vawda.