Added copy() to inner loop of OpFromGraph.perform to workaround borrowed output

theano/compile/builders.py

@@ -80,8 +80,11 @@ class OpFromGraph(gof.Op):
 
     def perform(self, node, inputs, outputs):
         variables = self.fn(*inputs)
+        assert len(variables) == len(outputs)
         for output, variable in zip(outputs, variables):
-            output[0] = variable
+            ##TODO: when function's output-borrowing semantics are correct, we wont need this
+            # copy anymore
+            output[0] = variable.copy()
 
     def grad(self, inputs, output_grads):
         if hasattr(self, 'grad_ops'):