--- a/mercurial/context.py	Tue Sep 18 21:39:12 2012 +0900
+++ b/mercurial/context.py	Tue Sep 18 21:39:12 2012 +0900
@@ -288,6 +288,10 @@
         n = self._repo.changelog.ancestor(self._node, n2)
         return changectx(self._repo, n)
 
+    def descendant(self, other):
+        """True if other is descendant of this changeset"""
+        return self._repo.changelog.descendant(self._rev, other._rev)
+
     def walk(self, match):
         fset = set(match.files())
         # for dirstate.walk, files=['.'] means "walk the whole tree".