fixed critical bug in perform_like_c applied to single-output ops

gof/lib.py

@@ -223,7 +223,8 @@ class PythonOp(Op):
     def _perform(self):
         results = self._impl()
         if self.nout == 1:
-            self.out.set_value(results)
+            #self.out.set_value(results)
+            self.outputs[0].data = results
         else:
             assert self.nout == len(results)
             for result, output in zip(results, self.outputs):
@@ -232,7 +233,7 @@ class PythonOp(Op):
     def _perform_like_c(self):
         results = self._impl()
         if self.nout == 1:
-            self.out.set_value(results)
+            self.outputs[0].data[:] = results
         else:
             assert self.nout == len(results)
             for result, output in zip(results, self.outputs):