diff -r 2d3cbcace897 -r df52ff0980fe mercurial/revset.py
--- a/mercurial/revset.py	Fri Aug 13 13:16:34 2010 -0400
+++ b/mercurial/revset.py	Fri Aug 13 13:11:41 2010 -0300
@@ -378,6 +378,12 @@
     l.reverse()
     return l
 
+def present(repo, subset, x):
+    try:
+        return getset(repo, subset, x)
+    except error.RepoLookupError:
+        return []
+
 def sort(repo, subset, x):
     l = getargs(x, 1, 2, _("sort wants one or two arguments"))
     keys = "rev"
@@ -481,6 +487,7 @@
     "p1": p1,
     "p2": p2,
     "parents": parents,
+    "present": present,
     "removes": removes,
     "reverse": reverse,
     "roots": roots,