diff -r 40411ad2f5d2 -r 5effb1992c17 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Fri Oct 23 15:59:32 2020 -0700
+++ b/mercurial/filemerge.py	Mon Oct 26 10:33:32 2020 -0700
@@ -643,7 +643,7 @@
 
 
 def _describemerge(ui, repo, mynode, fcl, fcb, fco, env, toolpath, args):
-    tmpl = ui.config(b'ui', b'pre-merge-tool-output-template')
+    tmpl = ui.config(b'command-templates', b'pre-merge-tool-output')
     if not tmpl:
         return