--- a/hgext/histedit.py	Fri Jan 10 13:12:24 2020 -0800
+++ b/hgext/histedit.py	Tue Jan 28 14:53:23 2020 -0800
@@ -649,7 +649,7 @@
             repo.ui.setconfig(
                 b'ui', b'forcemerge', opts.get(b'tool', b''), b'histedit'
             )
-            stats = mergemod.graft(repo, ctx, ctx.p1(), [b'local', b'histedit'])
+            stats = mergemod.graft(repo, ctx, labels=[b'local', b'histedit'])
         finally:
             repo.ui.setconfig(b'ui', b'forcemerge', b'', b'histedit')
     return stats