diff -r a09cc6aeed4a -r 632fa86aac55 mercurial/revset.py
--- a/mercurial/revset.py	Fri Jul 20 19:08:26 2012 -0400
+++ b/mercurial/revset.py	Sat Jul 28 23:51:57 2012 +0900
@@ -1424,7 +1424,7 @@
 
 def unstable(repo, subset, x):
     """``unstable()``
-    Unstable changesets are non-obsolete with obsolete descendants."""
+    Unstable changesets are non-obsolete with obsolete ancestors."""
     # i18n: "unstable" is a keyword
     getargs(x, 0, 0, _("unstable takes no arguments"))
     unstableset = set(repo.revs('(obsolete()::) - obsolete()'))