diff -r ed91846c29cf -r 284fa44f7f39 mercurial/filemerge.py
--- a/mercurial/filemerge.py	Fri Oct 06 06:48:43 2017 -0700
+++ b/mercurial/filemerge.py	Fri Oct 06 06:48:43 2017 -0700
@@ -739,6 +739,7 @@
         if r:
             if onfailure:
                 ui.warn(onfailure % fd)
+            _onfilemergefailure(ui)
 
         return True, r, deleted
     finally: