Fix bug for UT test_calc_gradient (#41130)

python/paddle/fluid/tests/unittests/test_calc_gradient.py

@@ -122,6 +122,7 @@ class TestDoubleGradient(unittest.TestCase):
         return start_prog, main_prog, [grad_x, jvp]
 
     def test_calc_gradient(self):
+        with paddle.fluid.scope_guard(paddle.static.Scope()):
             start_prog, main_prog, fetch_list = self.build_program()
             exe = paddle.static.Executor()
             exe.run(start_prog)
@@ -158,6 +159,7 @@ class TestDoubleGradient2(unittest.TestCase):
         return start_prog, main_prog, [grad_x, jvp]
 
     def test_calc_gradient(self):
+        with paddle.fluid.scope_guard(paddle.static.Scope()):
             start_prog, main_prog, fetch_list = self.build_program()
             exe = paddle.static.Executor()
             exe.run(start_prog)