bpo-26184: import.rst: Improve versionchanged note (GH-277) (#320)

(cherry picked from commit 6b4a5f45e2df524174a97832571c82c76a3d424a)
diff --git a/Doc/reference/import.rst b/Doc/reference/import.rst
index b603d1f..484457a 100644
--- a/Doc/reference/import.rst
+++ b/Doc/reference/import.rst
@@ -464,8 +464,11 @@
 
 .. versionchanged:: 3.5
    A :exc:`DeprecationWarning` is raised when ``exec_module()`` is defined but
-   ``create_module()`` is not. Starting in Python 3.6 it will be an error to not
-   define ``create_module()`` on a loader attached to a ModuleSpec.
+   ``create_module()`` is not.
+
+.. versionchanged:: 3.6
+   An :exc:`ImportError` is raised when ``exec_module()`` is defined but
+   ``create_module`` is not.
 
 Submodules
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