diff -r 62b29ca72d1a -r 11025c4f1016 mercurial/configitems.py
--- a/mercurial/configitems.py	Sat Jul 15 14:14:53 2017 +0200
+++ b/mercurial/configitems.py	Fri Jun 30 03:44:56 2017 +0200
@@ -484,6 +484,14 @@
 coreconfigitem('ui', 'mergemarkers',
     default='basic',
 )
+coreconfigitem('ui', 'mergemarkertemplate',
+    default=('{node|short} '
+            '{ifeq(tags, "tip", "", '
+            'ifeq(tags, "", "", "{tags} "))}'
+            '{if(bookmarks, "{bookmarks} ")}'
+            '{ifeq(branch, "default", "", "{branch} ")}'
+            '- {author|user}: {desc|firstline}')
+)
 coreconfigitem('ui', 'nontty',
     default=False,
 )