Rename grad2 to L_op.

theano/gof/op.py

@@ -696,7 +696,7 @@ class PureOp(object):
     # Python implementation #
     #########################
 
-    def grad2(self, inputs, outputs, output_grads):
+    def L_op(self, inputs, outputs, output_grads):
         return self.grad(inputs, output_grads)
 
     def R_op(self, inputs, eval_points):

theano/gradient.py

@@ -1102,7 +1102,7 @@ def _populate_grad_dict(var_to_app_to_idx,
                                 str(o_shape) + " on an output of shape " +
                                 str(g_shape))
 
-                input_grads = node.op.grad2(inputs, node.outputs,
+                input_grads = node.op.L_op(inputs, node.outputs,
                                            new_output_grads)
 
                 if input_grads is None: