Issue #12599: Be more strict in accepting None vs. a false-like object
in importlib.

Thanks to PJE for pointing out the issue and Nick Coghlan for filing
the bug.
diff --git a/Misc/NEWS b/Misc/NEWS
index 9f0009f..5c0c1c6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@
 Core and Builtins
 -----------------
 
+- Issue #12599: Be more strict in accepting None compared to a false-like
+  object for importlib.util.module_for_loader and
+  importlib.machinery.PathFinder.
+
 - Issue #14592: Attempting a relative import w/o __package__ or __name__ set in
   globals raises a KeyError.