hgext/mq.py

--- a/hgext/mq.py	Fri Jan 17 21:22:23 2020 +0300
+++ b/hgext/mq.py	Fri Jan 24 15:28:37 2020 -0800
@@ -858,7 +858,7 @@
         strip(self.ui, repo, [n], update=False, backup=False)
 
         ctx = repo[rev]
-        ret = hg.merge(repo, rev)
+        ret = hg.merge(ctx)
         if ret:
             raise error.Abort(_(b"update returned %d") % ret)
         n = newcommit(repo, None, ctx.description(), ctx.user(), force=True)