Patch #1467770: Add Popen objects to _active only in __del__.
Introduce _child_active member to keep track on whether a child
needs to be waited for.
Backport candidate.
diff --git a/Misc/NEWS b/Misc/NEWS
index f874a2d..bac4238 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -26,6 +26,9 @@
 Library
 -------
 
+- Patch #1467770: Reduce usage of subprocess._active to processes which
+  the application hasn't waited on.
+
 - Patch #1462222: Fix Tix.Grid.
 
 - Fix exception when doing glob.glob('anything*/')