--- a/mercurial/hbisect.py	Tue Aug 23 17:31:13 2022 -0400
+++ b/mercurial/hbisect.py	Tue Aug 23 17:31:19 2022 -0400
@@ -39,7 +39,7 @@
     def buildancestors(bad, good):
         badrev = min([changelog.rev(n) for n in bad])
         ancestors = collections.defaultdict(lambda: None)
-        for rev in repo.revs(b"descendants(%ln) - ancestors(%ln)", good, good):
+        for rev in repo.revs(b"(%ln::%d) - (::%ln)", good, badrev, good):
             ancestors[rev] = []
         if ancestors[badrev] is None:
             return badrev, None