Merge pull request #868 from pascanur/fix_pushout_opt

theano/scan_module/scan_opt.py

@@ -297,8 +297,11 @@ class PushOutNonSeqScan(gof.Optimizer):
                                                    *shape)
 
             # We need to add one extra dimension to the outputs
-            fgraph.replace_all_validate(replace_with.items(),
-                                     reason='scan_push_computation_out')
+            if replace_with:
+                fgraph.replace_all_validate_remove(
+                    replace_with.items(),
+                    remove=[node],
+                    reason='scan_push_computation_out')
 
         else:
             return False