basectx: move __ne__ from changectx

basectx: move __ne__ from changectx

--- a/mercurial/context.py	Mon Aug 05 17:00:09 2013 -0500
+++ b/mercurial/context.py	Mon Aug 05 17:00:32 2013 -0500
@@ -50,6 +50,9 @@
         except AttributeError:
             return False
 
+    def __ne__(self, other):
+        return not (self == other)
+
     def rev(self):
         return self._rev
     def node(self):
@@ -168,9 +171,6 @@
         except AttributeError:
             return id(self)
 
-    def __ne__(self, other):
-        return not (self == other)
-
     def __nonzero__(self):
         return self._rev != nullrev