diff --git a/contrib/revsetbenchmarks.txt b/contrib/revsetbenchmarks.txt
--- a/contrib/revsetbenchmarks.txt
+++ b/contrib/revsetbenchmarks.txt
@@ -17,6 +17,7 @@ min(0::)
 # those two `roots(...)` inputs are close to what phase movement use.
 roots((tip~100::) - (tip~100::tip))
 roots((0::) - (0::tip))
+42:68 and roots(42:tip)
 ::p1(p1(tip))::
 public()
 :10000 and public()
diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -1684,7 +1684,7 @@ def roots(repo, subset, x):
     Changesets in set with no parent changeset in set.
     """
     s = getset(repo, fullreposet(repo), x)
-    subset = baseset([r for r in s if r in subset])
+    subset = subset & s# baseset([r for r in s if r in subset])
     cs = _children(repo, subset, s)
     return subset - cs