--- a/mercurial/revset.py	Thu Feb 06 08:31:55 2014 -0800
+++ b/mercurial/revset.py	Thu Feb 06 08:32:40 2014 -0800
@@ -571,7 +571,7 @@
         source = repo[r].extra().get('convert_revision', None)
         return source is not None and (rev is None or source.startswith(rev))
 
-    return baseset([r for r in subset if _matchvalue(r)])
+    return lazyset(subset, lambda r: _matchvalue(r))
 
 def date(repo, subset, x):
     """``date(interval)``