Update comment in cython backend

theano/scan_module/scan_perform.pyx

@@ -340,9 +340,12 @@ def perform(
             pdx = offset + n_shared_outs
             output_storage[<unsigned int>pdx].storage[0] = None
 
-        # 4.5. Keep a reference to the variables currently in the
-        # output_storage, and their data, to be able to compare them with
-        # the actual outputs of the inner function after its execution
+        # 4.5. Keep a reference to the variables (ndarrays, CudaNdarrays,
+        # etc) currently in the output_storage to be able to compare them
+        # with the actual outputs of the inner function after its
+        # execution. Also keep pointers to their data to be able to detect
+        # cases where outputs reused the allocated object but alter the
+        # memory region they refer to.
         for idx in range(len_output_storage):
 
             var = output_storage[idx].storage[0]