--- a/hgext3rd/topic/stack.py	Fri Sep 06 12:53:46 2019 +0700
+++ b/hgext3rd/topic/stack.py	Fri Sep 06 13:23:25 2019 +0700
@@ -155,7 +155,6 @@
                 dependencies[k] = [i.copy() for i in v]
             else:
                 dependencies[k] = v.copy()
-        rdependencies = rdependencies.copy()
         # Step 2: Build the ordering
         # Remove the revisions with no dependency(A) and add them to the ordering.
         # Removing these revisions leads to new revisions with no dependency (the