--- a/hgext3rd/topic/evolvebits.py	Wed Nov 27 20:54:48 2019 +0530
+++ b/hgext3rd/topic/evolvebits.py	Thu Dec 19 22:31:13 2019 -0800
@@ -81,7 +81,7 @@
         ui.debug(b"stabilize target %s is plain dead,"
                  b" trying to stabilize on its parent\n" %
                  obs)
-        obs = obs.parents()[0]
+        obs = obs.p1()
         newer = obsutil.successorssets(repo, obs.node())
     if 1 < len(newer):
         # divergence case