--- a/mercurial/help/config.txt	Wed Jul 01 15:12:45 2015 -0500
+++ b/mercurial/help/config.txt	Mon Jun 29 12:35:31 2015 -0400
@@ -1291,6 +1291,10 @@
     checking that all new file revisions specified in manifests are
     present. Default is False.
 
+``maxhttpheaderlen``
+    Instruct HTTP clients not to send request headers longer than this
+    many bytes. Default is 1024.
+
 ``smtp``
 --------