mercurial/commands.py

--- a/mercurial/commands.py	Sat Apr 14 18:36:00 2018 -0700
+++ b/mercurial/commands.py	Sat Apr 14 20:04:59 2018 -0700
@@ -4037,7 +4037,9 @@
                 oldrevs = revs
                 revs = [] # actually, nodes
                 for r in oldrevs:
-                    node = other.lookup(r)
+                    with other.commandexecutor() as e:
+                        node = e.callcommand('lookup', {'key': r}).result()
+
                     revs.append(node)
                     if r == checkout:
                         checkout = node