minor fix

theano/gof/graph.py

@@ -97,7 +97,6 @@ class Apply(Node):
         self.op = op
         self.inputs = []
         self.tag = utils.scratchpad()
-        utils.add_tag_trace(self)
 
         if not isinstance(inputs, (list, tuple)):
             raise TypeError("The inputs of an Apply must be a list or tuple")
@@ -118,7 +117,8 @@ class Apply(Node):
                 if output.owner is None:
                     output.owner = self
                     output.index = i
-                    output.tag = utils.scratchpad()
+                    if not hasattr(output, "tag"):
+                        output.tag = utils.scratchpad()
                     utils.add_tag_trace(output)
                 elif output.owner is not self or output.index != i:
                     raise ValueError("All output variables passed to Apply must belong to it.")

theano/gof/op.py

@@ -613,7 +613,6 @@ class PureOp(object):
         """
         return_list = kwargs.pop('return_list', False)
         node = self.make_node(*inputs, **kwargs)
-        utils.add_tag_trace(node)
 
         if config.compute_test_value != 'off':
             run_perform = True

theano/printing.py

@@ -308,8 +308,6 @@ class Print(Op):
         self.message = message
         self.attrs = tuple(attrs)  # attrs should be a hashable iterable
         self.global_fn = global_fn
-        self.tag = gof.utils.scratchpad()
-        gof.utils.add_tag_trace(self)
 
     def make_node(self, xin):
         xout = xin.type.make_variable()