diff -r 2d0c306a88c2 -r 1826d695ad58 mercurial/configitems.py
--- a/mercurial/configitems.py	Tue Sep 26 16:14:57 2017 +0300
+++ b/mercurial/configitems.py	Thu Sep 21 15:58:44 2017 +0530
@@ -176,6 +176,9 @@
 coreconfigitem('experimental', 'copytrace',
     default='on',
 )
+coreconfigitem('experimental', 'copytrace.sourcecommitlimit',
+    default=100,
+)
 coreconfigitem('experimental', 'crecordtest',
     default=None,
 )