diff -r 7deeecfc49b3 Doc/library/pkgutil.rst
--- a/Doc/library/pkgutil.rst	Fri Dec 09 18:51:13 2016 +0100
+++ b/Doc/library/pkgutil.rst	Fri Dec 09 17:03:21 2016 -0800
@@ -224,4 +224,6 @@
 
    If the package cannot be located or loaded, or it uses a :term:`loader`
    which does not support :meth:`get_data <importlib.abc.ResourceLoader.get_data>`,
-   then ``None`` is returned.
+   then ``None`` is returned.  In particular, the :term:`loader` for
+   :term:`namespace packages <namespace package>` does not support
+   :meth:`get_data <importlib.abc.ResourceLoader.get_data>`.