mercurial/cmdutil.py

--- a/mercurial/cmdutil.py	Wed May 17 22:33:15 2017 -0700
+++ b/mercurial/cmdutil.py	Tue May 09 16:29:31 2017 -0700
@@ -2741,7 +2741,7 @@
                     if node:
                         obs.append((ctx, ()))
 
-                    obsolete.createmarkers(repo, obs)
+                    obsolete.createmarkers(repo, obs, operation='amend')
         if not createmarkers and newid != old.node():
             # Strip the intermediate commit (if there was one) and the amended
             # commit