Fix crash as we sometimes still have Composite in Composite.

theano/scalar/basic.py

@@ -3658,6 +3658,8 @@ class Composite(ScalarOp):
 
     def prepare_node(self, node, storage_map, compute_map):
         self.init_py_impls()  # self._impls
+        for n in theano.gof.graph.list_of_nodes(self.inputs, self.outputs):
+            n.op.prepare_node(n, None, None)
 
     def output_types(self, input_types):
         if tuple(input_types) != self.inputs_type: