Don't raise an error for test value when the compute_test_value is off during opt.

theano/tensor/opt.py

@@ -4656,9 +4656,10 @@ def local_elemwise_fusion_op(OP, max_input_fct=lambda node: 1024):
                 else:
                     s = scalar.Scalar(i.dtype).make_variable()
                     try:
-                        v = gof.op.get_test_value(i)
-                        if v.size > 0:
-                            s.tag.test_value = gof.op.get_test_value(i).flatten()[0]
+                        if theano.config.compute_test_value != 'off':
+                            v = gof.op.get_test_value(i)
+                            if v.size > 0:
+                                s.tag.test_value = v.flatten()[0]
                     except AttributeError:
                         pass