Update whatsnew based on doc search.
diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index 3dfa2cc..53d8981 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -841,7 +841,7 @@
    will always return ``True`` except if a timeout is given and the operation
    times out.
 
-   .. versionchanged:: 2.7
+   .. versionchanged:: 3.1
       Previously, the method always returned ``None``.
 
 .. class:: Lock()