diff -r f5b366a31740 -r a4d081923c81 hgext3rd/topic/discovery.py
--- a/hgext3rd/topic/discovery.py	Tue Mar 10 19:04:33 2020 +0700
+++ b/hgext3rd/topic/discovery.py	Tue Mar 10 19:05:08 2020 +0700
@@ -157,7 +157,7 @@
         return
     tr._prepushheads = _nbheads(op.repo)
     reporef = weakref.ref(op.repo)
-    if util.safehasattr(tr, 'validator'): # hg <= 4.7
+    if util.safehasattr(tr, 'validator'): # hg <= 4.7 (ebbba3ba3f66)
         oldvalidator = tr.validator
     else:
         oldvalidator = tr._validator
@@ -178,7 +178,7 @@
                             % branch)
                     raise error.Abort(msg)
         return oldvalidator(tr)
-    if util.safehasattr(tr, 'validator'): # hg <= 4.7
+    if util.safehasattr(tr, 'validator'): # hg <= 4.7 (ebbba3ba3f66)
         tr.validator = validator
     else:
         tr._validator = validator