Issue #14605: Make explicit the entries on sys.path_hooks that used to
be implicit.

Added a warning for when sys.path_hooks is found to be empty. Also
changed the meaning of None in sys.path_importer_cache to represent
trying sys.path_hooks again (an interpretation of previous semantics).
Also added a warning for when None was found.

The long-term goal is for None in sys.path_importer_cache to represent
the same as imp.NullImporter: no finder found for that sys.path entry.
diff --git a/Misc/NEWS b/Misc/NEWS
index f0f0807..21cead0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,11 @@
 Core and Builtins
 -----------------
 
+- Issue #14605: No longer have implicit entries in sys.path_hooks. If
+  sys.path_hooks is found to be empty, a warning will be raised. If None is
+  found in sys.path_importer_cache, a warning is raised and a search on
+  sys.path_hooks is attempted.
+
 - Issue #13903: Implement PEP 412. Individual dictionary instances can now share
   their keys with other dictionaries. Classes take advantage of this to share
   their instance dictionary keys for improved memory and performance.