Changed clip() from transfer_type(0) to upcast_out

theano/scalar/basic.py

@@ -904,9 +904,7 @@ class Clip(ScalarOp):
             return gx, None, None
         else:
             return None, None, None
-
-        #return gx if x.type in grad_types else None, None, None
-clip = Clip(transfer_type(0), name = 'clip')
+clip = Clip(upcast_out, name = 'clip')
 
 class First(BinaryScalarOp):
     def impl(self, x, y):