mercurial/cmdutil.py

--- a/mercurial/cmdutil.py	Fri Aug 03 00:10:52 2018 +0530
+++ b/mercurial/cmdutil.py	Tue Jul 10 20:23:55 2018 +0530
@@ -2556,8 +2556,10 @@
         obsmetadata = None
         if opts.get('note'):
             obsmetadata = {'note': encoding.fromlocal(opts['note'])}
+        backup = ui.configbool('ui', 'history-editing-backup')
         scmutil.cleanupnodes(repo, mapping, 'amend', metadata=obsmetadata,
-                             fixphase=True, targetphase=commitphase)
+                             fixphase=True, targetphase=commitphase,
+                             backup=backup)
 
         # Fixing the dirstate because localrepo.commitctx does not update
         # it. This is rather convenient because we did not need to update