Document when json.load's parse_constant behaviour changed
It doesn't get called on 'null', 'true', 'false' since f686aced02a3.
diff --git a/Doc/library/json.rst b/Doc/library/json.rst
index cbcac8d..b20709f 100644
--- a/Doc/library/json.rst
+++ b/Doc/library/json.rst
@@ -213,6 +213,9 @@
This can be used to raise an exception if invalid JSON numbers
are encountered.
+ .. versionchanged:: 2.7
+ *parse_constant* doesn't get called on 'null', 'true', 'false' anymore.
+
To use a custom :class:`JSONDecoder` subclass, specify it with the ``cls``
kwarg; otherwise :class:`JSONDecoder` is used. Additional keyword arguments
will be passed to the constructor of the class.