diff -r ab7b4fba8bde -r abc327f9628b contrib/perf-utils/subsetmaker.py
--- a/contrib/perf-utils/subsetmaker.py	Mon Jan 06 01:06:59 2025 -0500
+++ b/contrib/perf-utils/subsetmaker.py	Mon Jan 06 01:12:54 2025 -0500
@@ -83,7 +83,7 @@
 
     selected = set()
     heads = SortedSet()
-    children_count = collections.defaultdict(lambda: 0)
+    children_count = collections.defaultdict(int)
     parents = repo.changelog._uncheckedparentrevs
 
     baseset = revset.getset(repo, smartset.fullreposet(repo), x)