bpo-41898: add caveat on root logger seeing all messages in assertLogs doc (GH-22526) (GH-22540)

miss-islington · web-flow · commit faa8c6a8f1fe · 2020-10-04T16:38:03.000+01:00
(cherry picked from commit 1ed5443)
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
@@ -1088,7 +1088,8 @@ Test cases
 
       If given, *logger* should be a :class:`logging.Logger` object or a
       :class:`str` giving the name of a logger.  The default is the root
-      logger, which will catch all messages.
+      logger, which will catch all messages that were not blocked by a
+      non-propagating descendent logger.
 
       If given, *level* should be either a numeric logging level or
       its string equivalent (for example either ``"ERROR"`` or
