diff -r 592feb3f88b1 -r 86dfae98a3a2 mercurial/configitems.py
--- a/mercurial/configitems.py	Fri Oct 26 21:46:37 2018 +0900
+++ b/mercurial/configitems.py	Sat Oct 13 07:49:20 2018 -0700
@@ -1193,6 +1193,9 @@
 coreconfigitem('ui', 'patch',
     default=None,
 )
+coreconfigitem('ui', 'pre-merge-tool-output-template',
+    default=None,
+)
 coreconfigitem('ui', 'portablefilenames',
     default='warn',
 )