added a bunch of extra comments

theano/scan_module/scan_opt.py

@@ -75,9 +75,10 @@ def remove_constants_and_unused_inputs_scan(node):
         if (isinstance(node.inputs[idx+1], tensor.TensorConstant) and
             node.inputs[idx+1].tag.unique_value is not None):
             try:
-                val = tensor.get_constant_value(node.inputs[idx+1],
-                                                return_ndarray = True)
-                givens[op_ins[idx]] = tensor.constant(val[0])
+                # This works if input is a constant that has all entries
+                # equal
+                val = tensor.get_constant_value(node.inputs[idx+1])
+                givens[op_ins[idx]] = node.inputs[idx+1].clone()[0]
             except TypeError:
                 pass
         elif op_ins[idx] in all_ins:
@@ -99,6 +100,7 @@ def remove_constants_and_unused_inputs_scan(node):
         op_outs = scan_utils.clone(op_outs, replace = givens)
         nw_info = op.info.copy()
         nw_info['n_seqs'] = nw_n_seqs
+        # DEBUG CHECK
         nwScan = scan_op.Scan(nw_inner, op_outs, nw_info)
         nw_outs = nwScan.make_node(*nw_outer).outputs
         return nw_outs