Document the import semantics that if None is found in sys.modules for a module then ImportError is raised.
diff --git a/Doc/reference/simple_stmts.rst b/Doc/reference/simple_stmts.rst
index 2a34b69..7387da7 100644
--- a/Doc/reference/simple_stmts.rst
+++ b/Doc/reference/simple_stmts.rst
@@ -668,7 +668,9 @@
"module" will refer to both packages and modules), searching
for the module or package can begin. The first place checked is
:data:`sys.modules`, the cache of all modules that have been imported
-previously. If the module is found there then it is used in step (2) of import.
+previously. If the module is found there then it is used in step (2) of import
+unless :keyword:`None` is found in :data:`sys.modules`, in which case
+:exc:`ImportError` is raised.
.. index::
single: sys.meta_path
diff --git a/Misc/NEWS b/Misc/NEWS
index ea061a7..5189aae 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -174,6 +174,9 @@
Documenation
------------
+- Document that importing a module that has None in sys.modules triggers an
+ ImportError.
+
- Issue #6556: Fixed the Distutils configuration files location explanation
for Windows.