--- a/hgext/mq.py	Fri Jan 25 23:43:11 2019 -0800
+++ b/hgext/mq.py	Fri Jan 25 23:22:23 2019 -0800
@@ -970,7 +970,7 @@
                         repo.dirstate.remove(f)
                     for f in merged:
                         repo.dirstate.merge(f)
-                    p1, p2 = repo.dirstate.parents()
+                    p1 = repo.dirstate.p1()
                     repo.setparents(p1, merge)
 
             if all_files and '.hgsubstate' in all_files: