reverted change

theano/tensor/elemwise.py

@@ -743,6 +743,8 @@ class Elemwise(Op):
             scalar_inputs = map(as_scalar, inputs)
             scalar_ograds = map(as_scalar, ograds)
             scalar_igrads = self.scalar_op.grad(scalar_inputs, scalar_ograds)
+            for igrad in scalar_igrads:
+                assert igrad is not None
 
         finally: