--- a/mercurial/obsolete.py	Fri Jan 04 03:15:44 2013 +0100
+++ b/mercurial/obsolete.py	Fri Jan 04 03:16:08 2013 +0100
@@ -677,7 +677,7 @@
 @cachefor('extinct')
 def _computeextinctset(repo):
     """the set of obsolete parents without non obsolete descendants"""
-    return set(repo.revs('obsolete() - obsolete()::unstable()'))
+    return getrevs(repo, 'obsolete') - getrevs(repo, 'suspended')
 
 
 @cachefor('bumped')