basectx: move __contains__ from changectx

mercurial/context.py

@@ -53,6 +53,9 b' class basectx(object):'
     def __ne__(self, other):
         return not (self == other)
 
+    def __contains__(self, key):
+        return key in self._manifest
+
     @propertycache
     def substate(self):
         return subrepo.state(self, self._repo.ui)
@@ -197,9 +200,6 b' class changectx(basectx):'
             p = p[:-1]
         return [changectx(self._repo, x) for x in p]
 
-    def __contains__(self, key):
-        return key in self._manifest
-
     def __getitem__(self, key):
         return self.filectx(key)