diff -r 493470e7a0f2 -r 6b7ad4b50d00 hgext3rd/topic/stack.py
--- a/hgext3rd/topic/stack.py	Tue Jun 04 10:30:56 2019 +0200
+++ b/hgext3rd/topic/stack.py	Sun May 05 16:14:53 2019 +0800
@@ -318,7 +318,7 @@
         states = []
         if opts.get('children'):
             expr = 'children(%d) and merge() - %ld'
-            revisions = repo.revs(expr, ctx.rev(), st.revs[1:])
+            revisions = repo.revs(expr, ctx.rev(), st._revs)
             if len(revisions) > 0:
                 states.append('external-children')